changed unit declarations macros to make a lot more sense

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

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

changed LLCriticalDamp to LLSmoothInterpolation and sped up interpolator lookup
improvements to stats display of llstatbar
added scene load stats floater accessed with ctrl|shift|2

Ok, finally got this to a point where it doesn't break the build and I can check
in. llcommon can be built as a shared library (disabled but can be enabled with
cmake cache var LLCOMMON_LINK_SHARED.

reviewed by Mani on tuesday (I still need to get his suggested changes
re-reviewed)

Result of svn merge -r107256:107258 svn+ssh://svn/svn/user/phoenix/license_2009_merge into trunk. QAR-1165

Result of svn merge -r71162:71205 svn+ssh://svn/svn/linden/branches/new-license into release. only changes files which are not deployed or the comments section of code.