Apparently, in previous Boost versions, boost::noncopyable was sneaking into
the namespace via other headers. Now the compiler complains about its absence
without an explicit #include.

Id rather than sha1 hash, since that is rarely used in modern
certs. The previous form was storing trusted certs using an empty sha1
hash value as the key, which meant most certificates matched... not good.

Modify the LLCertException to pass certificate information back as
LLSD rather than an LLPointer<LLCertificate>, because when the
exception is being thown from the certificate constructor that results
in one of a couple of other exceptions (even refcounting won't save
you when the problem is that the thing you're pointing to never
finished coming into being properly).

Update the certificates in the llsechandler_basic_test to modern
conventions, and extend the classes to allow for an optional
validation date so that the test can use a fixed date. Also make all
the certificates include the plain text form for ease of reference.

Turns out that Monty didn't intend for the int-flavored representation of
HttpStatus to expand to 64 bits even when unsigned long is that wide. So
change the implicit conversion operator, and its uses, to U32 instead. That
produces a consistent toHex() result for both 32-bit and 64-bit builds.

MAINT-5271: Converted internal pointers to internal operation to managed shared pointers. Removed direct cast and dereference of handles.

Event polling as a coroutine. (incomplete)
Groundwork for canceling HttpCoroutineAdapter yields.

Prep for some slight cleanup of the code.
Add AP_AVATAR Policy

Start using DNS cache in legacy LLCurl code.  Go to 15 seconds
particularly as we're using threaded resolver at this point.
Documentation cleanup.  Add libcurl status checking and logging
for curl_easy_setopt() operations that fail.  Shouldn't happen
and we'll just continue anyway but there's info in the logs to
track these down now.  Cleaned up logic around FASTTIMER enable
defines used to evaluate pipeline stalls in main thread.
Removed long-standing thread race around caps strings and
URL construction.  Not a significant risk but refactoring the
code to get rid of them removed one huge eyesore.  It can be
made even slicker if desired (see notes).

Added toTerseString() conversion on HttpStatus to generate a string
that's more descriptive than the hex value of the HttpStatus value
but still forms a short, searchable token (e.g. "Http_503" or
"Core_7").  Using this throughout the viewer now, no live cases
of toHex(), I believe.

Much improved.  Unified the global and class options into a single
option list.  Implemented static and dynamic setting paths as much
as possible.  Dynamic path does require packet/RPC but otherwise
there's near unification.  Dynamic modes can't get values back yet
due to the response/notifier scheme but this doesn't bother me.
Flatten global and class options into simpler struct-like entities.
Setter/getter available on these when needed (external APIs) but code
can otherwise fiddle directly when it knows what to do.  Much duplicated
options/state removed from HttpPolicy.  Comments cleaned up.  Threads
better described and consistently mentioned in API docs.  Integration
test extended for 503 responses with Reply-After headers.

Not certain what the source of the short data is with one resident but I'm
going to make these problems retryable as they are transport-related.  Lift
the retry detection into a method that should be reusable by others interested
in determining what is retryable.  Trace output handling on the libcurl debug
callback was attrocious.  Some unsafe length handling on my part was protected
by a second layer of defense.  Made that correct and more useful by logging
actual data sizes during trace.

Add to-do list to _httpinternal.h to guide anyone who
wants to pitch in and help.

When releasing HTTP waiters, avoid unnecessary sort activity.
For Content-Type in responses, let libcurl do the work and removed
my parsing of headers.  Drop Content-Encoding as libcurl will deal
with that.  If anyone is interested, they can parse.

Also added some comments and changed the callback userdata argument
to be an HttpOpRequest rather than a libcurl handle.  Less code,
less clutter.

surprised me.  Added a retry queue similar to ready queue to the
policy object which is sorted by retry time.  Currently do five
retries (after the initial try) delayed by .25, .5, 1, 2 and 5
seconds.  Removed the retry logic from the lltexturefetch module.
Upped the waiting time in the unit test for the retries.  People
won't like this but tough, need tests.

Implemented first global policy definitions to support SSL CA certificate configuration
to support https: operations.  Fixed HTTP 206 status handling to match what is currently
being done by grid services and to lay a foundation for fixes that will be a response
to ER-1824.  More libcurl CURLOPT options set on easy handles to do peer verification
in the traditional way.  HTTP POST working and now reporting asset metrics back to
grid for the viewer's asset system.  This uses LLSD so that is also showing as compatible
with the new library.

Identified and reacted to the priority inversion problem we
have in texturefetch.  Includes the introduction of a priority_queue
for the requests that are ready.  Start some parameterization in
anticipation of having policy_class everywhere.  Removed _assert.h
which isn't really needed in indra codebase.  Implemented async
setPriority request (which I hope I can get rid of eventually along
with all priorities in this library).  Converted to using unsigned
int for priority rather than float.  Implemented POST and did
groundwork for PUT.

This is the first functional viewer pass with the HTTP work of the texture fetch
code performed by the llcorehttp library.  Not exactly a 'drop-in' replacement
but a work-alike with some changes (e.g. handler notification in consumer
thread versus responder notification in worker thread).

This also includes some temporary changes in the priority scheme to prevent
the kind of priority inversion found in VWR-28996.  Scheme used here does
provide liveness if not optimal responsiveness or order-of-operation.

The llcorehttp library at this point is far from optimally performing.
Its worker thread is making relatively poor use of cycles it gets and
it doesn't idle or sleep intelligently yet.  This early integration step
helps shake out the interfaces, implementation niceties will be covered
soon.

while allocating the first easy handle in a descent of the global initiailization
code but that doesn't seem to be a problem on TC machines.  Perhaps the static
linking is creating multiple data copies.  More work needed.

boost::thread and the easiest path to that was to go with the 1.48 Boost release
in the 3P tree (eliminating a fork for a modified 1.45 packaging).  One unit test,
the most important one, is failing in test_httprequest but that can be attended
to later.  This test issues a GET to http://localhost:2/ and that is hitting the
wire but the libcurl plumbing isn't delivering the failure, only the eventual
timeout.  An unexpected change in behavior.

Bring llcorehttp into the compile and link phases.  Windows looks okay though it's a dead library so far.

The unit/integration tests don't work yet as I'm still battling cmake/autobuild
as usual but first milestone passed.