Use offsetof in offset functions.
The old macros looked crazy and they basically used the same code
used in the offsetof() definition inside ANSI C. Compilers may provide
even more optimized versions. http://en.wikipedia.org/wiki/Offsetof
Merge pull request #314 from archSeer/master

Use offsetof in offset functions.
More offset macros in need of a change
Merge pull request #315 from archSeer/master

offset macros
Fixed incorrect size parameter for Q_vsnprintf in AI_BobaFett.cpp in Boba_Printf.
Use full buffer size for va in MP and SP rather than -1.
Don't use memset on a char pointer, its bad.