added unit tests for lltrace

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

of unit operators

gcc 4.1/4.2 support

continued conversion to units system
made units perform type promotion correctly and preserve type in arithmetic
e.g. can now do LLVector3 in units
added typedefs for remaining common unit types, including implicits

converted many values over to units system in effort to track down
source of 0 ping

fixed bad search and replace

added convenience types for units F32Seconds, etc.

SH-4346 FIX Interesting: some integer Statistics are displayed as floating point after crossing region boundary
fine-tuned heuristics for switching between mean and current values in stat bar display
added comments to LLUnits unit test

SH-4346 FIX: Interesting: some integer Statistics are displayed as floating point after crossing region boundary
made llerrs/infos/etc properly variadic wrt tags
LL_INFOS("A", "B", "C") works, for example
fixed unit tests
remove llsimplestat

replace llinfos, lldebugs, etc with new LL_INFOS(), LL_DEBUGS(), etc.

moved object cache sampling code so that it actually gets executed
default values for stats are NaN instead of 0 in many cases

revert some LLUnit changes to temporarily fix SH-4399: Interesting: Texture console MB Bound 0/384 and texture queue bounces once per second