MAINT-3193 FIXED crash with LLControlCache<bool>::LLControlCache: Control named RenderAutoMuteLoggingnot found.

the change made for MAINT-2347.  Large transfers are still
10 minutes.  Add/update to-do list and add some more info to
the FAQ in the Readme.

BUG-3982 add code to subtract the lack of not removing the removal of backfaces for particles (make particles render double-sided again)

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).

MAINT-3179 fix bad indexing of position info generating false alarms on range checks, issue with free of data now allocated contig with positions instead, and added copious amounts of llwarns to error return sites so 'invalid element' will be a reason to read the log and not a tease.

behavior and swap() as well.  Should probably do this
for the other queues at some point.

traditional swap-less object transfer.

Much earlier identified some thread races including two on mskininfoq
and mdecompositionq.  I actually hit one in testing the other day so
I'm fixing them now.  Put them under the mMutex lock and use the
mutex in such a way that main thread stalls are not added.

Last bit for this release.  Describe stream adapters and how
to select a policy class.  Slight changes to setup code to
make reality reflect documentation.

MAINT-3152 FIXED [MAINTENANCE RC] Confusing naming of Lighting and Shadows/Advanced Lighting Model options in graphics preferences

First edit complete.  Use the library in 15 minutes.  Describe the
code.  Refinements to the initial try.  Describe that code.  Still
to do:  more refinements, how to choose a policy class, FAQ.