Added: started support for x86 80bit floating point.
Changed: aggregates passed by value now use the llvm 'byval' parameter attribute, also lays ground work for
using other attributes.
Changed: eliminated a lot more std::vectorS, these showed up pretty much at the top when profiling!
Changed: performed other misc. cleanups.
Changed: halt expression now call the new llvm trap intrinsic instead of an assert(0).
Changed: dstress suite now passes -O0 by default, this only eliminates unreferenced globals, which speeds up
linking quite a bit.
Fixed a bunch of the built-in typeinfos for arrays, they did not inherit TypeInfo_Array.
Applied patch to tango/text/convert/Layout.d by fvbommel, closes#47 .
Cleaned up some type code.
Replaced uses of llvm::Type with LLType (a typedef), same for Value and Constant.
Fixed a few cases where typeinfo for user structs could be emitted multiple times, seems to still be some cases of this :/
