made fast timer stack thread local
added LLThreadLocalSingleton
made LLThreadLocalPointer obey pointer rules for const
added LLThreadLocalSingletonPointer for fast thread local pointers

fixed crash on exit by making LLInstanceTracker iterators use atomic iterator
nesting count for thread safety

improvements on lifetime of lltrace core data structures
tweaks to thread local pointer handling so that static constructors/destructors
can safely call functions that use lltrace

removed some potential data races
got memory stats recording in trace system

created memory tracking trace type
instrumented a few classes with memory tracking

added ability to query self time of block timers indepedently

further fixes for gcc builds

potential fixes for gcc builds

improved unit tests for LLUnit
renamed LLUnit to LLUnitImplicit with LLUnit being reserved for
explicit units

added unit tests for LLUnit

improved LLUnit compile time errors
removed cassert in favor of llstatic_assert

fixed gcc compile error
made LLCopyOnWritePointer contain an LLPointer, not derive from it
added type trait to control periodicrecording mean value type

changed thread id declaration to be local to llthread.cpp and use
currentID() uniformly across platforms

added copy constructor to periodic recording to allow snapshot generation
in fast timer view
fixed build errors

converted fast timer view over to new lltrace mechanisms

started moving fast timer historical stats over to LLTrace periodic
recording

fixed scale of reported times
moved reset calls to happen at same time so we don't show partial results

fixed crash when sending viewer asset stats

moved runtime timer tree topology information to separate array instead of recording stack

fixed precision of fast timer counts

hunting down bad values and crashes

fixes to merge

got new fast timer code to compile and run

eliminated min and max macros from windows.h
got rest of viewer to compile against llfasttimer changes

cleaning up build
moved most includes of windows.h to llwin32headers.h to disable min/max macros, etc
streamlined Time class and consolidated functionality in BlockTimer class
llfasttimer is no longer included via llstring.h, so had to add it manually in several places

moving fast timers into lltrace namespace and accumulation system

MAINT-1891: FIX Updating the LLPipeline::clearRebuildGroups() to preserve HUD groups.  clearRebuildGroups() is called during the teleport process.  In the previous state, HUD objects were being incorrectly removed from the rebuild groups during the teleport process.  This change will preserve HUD groups and should resolve this issue.