Massive libyasm / module interface update - Phase 2 (finally).

Massive libyasm / module interface update - Phase 2 (finally).

(Hopefully) finish cleanups begun in phase 1 (see phase 1 commit message),
making dbgfmt, objfmt, optimizer, and preproc module interfaces follow the
same thread-safe interface style as the phase 1 changes.

Also put in a large number of doxygen documentation cleanups.

svn path=/trunk/yasm/; revision=1097