Previous logic could possibly leave mStartTime uninitialized, producing fatal
warnings with gcc 4.7.

Fasttimers: Windows) Always use the __rdtsc() intrinsic rather than inline assembly. Linux/OSX) The rtdsc assembly intruction is clobbering EAX and EDX, the snippet was not protecting EDX accordingly.
(transplanted from 6307b134f821390367d4c86a03b9a492ac7ed282)

(transplanted from ee32840fc591f5529a0b544243e7b4146eb8f531)

updates appearance utility dependency

added flag to LLInstanceTracker to allow multiple values per key
made StatType allow multiple values per key to eliminate block timer related crash

added more MemTrackable types
optimized memory usage of LLTrace some more

removed complicated and unnecessary fast timer gapless handoff logic (it should be gapless anyway)
improved MemTrackable API, better separation of shadow and footprint
added memory usage stats to floater_stats.xml

renamed "current" to "primary" when referring to accumulators

another attempt to move mem stat into base class

made getPrimaryAccumulator return a reference since it was an
always non-null pointer
changed unit conversion to perform lazy division in order to avoid truncation
of timer values

added convenience types for units F32Seconds, etc.

removed LLThreadLocalSingleton
collapsed all thread recorder classes to single type, LLTrace::ThreadRecorder
moved fasttimer stack head to llthreadlocalsingletonpointer via ThreadRecorder

fixed some lltrace logic errors
more consistent syncing of timestamps of sample values in recording stack
selection of primary buffers was completely incorrect
assignment of recordings got wrong play state due to implicit
operator = defined in base class
fixed asset stats only working up to the first send

moved collapsed flag to fast timer tree node

removed implicit flushes on reads from recorders for better performance
made sure stack timers were updated on recorder deactivate
faster rendering and better ui for fast timer view

changed Units macros and argument order to make it more clear
optimized units for integer types
fixed merging of periodicrecordings...should eliminate duplicate entries in sceneloadmonitor history

fixed mem stat tracking...now properly tracks memory footprint with floating point
precision
cleaned up macros for unit declaration
renamed units to SI standard for 1024 multiples (kibibytes, etc)
fixed units output for scene monitor dump

fix for inaccurate optimization of full block time calculations

streamlined fast timer delta tracking

fixed anamolous LLFastTimer timings

added debug output to BlockTimer

fix for timings for recursive fast timers not being correct

A couple of merge issues that caused the resulting code to not build.

fixed crash on startup

fixed some uninitialized variables
root timer accumulator was being initialized to NULL

improved performance of fast timer stat gathering

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

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