Intel SSE2 was merged into the main codebase.
Added more ARM, MIPS, and PowerPC optimizations, though some of them
aren't currently used by CMakeLists.txt.
I've decided to get rid of the GDI+ PNG handling. It doesn't improve
anything performance-wise, adds coding overhead, and probably isn't
any faster than libpng.
GDI+ also doesn't support APNG. This version does.
NOTE: If I add APNG export, I'll need to use the included libpng
in Ubuntu builds, since Ubuntu still has libpng-1.2, and it's a
version that doesn't support APNG.
Reworked the bundled library system to be similar to the one in
mcrecover, but improved.
Added "-fpic -fPIC" to all extlib static libraries when building
for Linux systems. This is needed for libpng, but might not be
needed for other libraries; nevertheless, it should be set.
TODO: Use libpng in the Windows build. It's being linked in,
but it isn't actually being used for anything yet.
