Clarify which mixer is which in al_attach_mixer_to_mixer's documentation
Document that al_set_new_bitmap_format takes ALLEGRO_PIXEL_FORMAT as an argument
Disallow attaching a mixer to itself.

This is somewhat of a corner case that was previous undocumented. I can't think
of a realistic usage for this that wouldn't imply an infinite recursion
somewhere.
Make al_load_ttf_font_stretch return NULL if invalid width/height are passed.

Previously this was undefined behavior, but it seems pointless to keep it that
way. If this feature is supported in the future, it makes a lot more sense to
have a clear signal when this feature is not supported than silently doing
something random.
Add the -pg flag to CMAKE_SHARED_LINKER_FLAGS_PROFILE to fix the profiling build.
typo in a comment
Added an experimental SDL port.

It's only use will be for testing.
typo in al_convert_bitmap

See https://www.allegro.cc/forums/thread/614454
ifdef out HLSL stuff when compiling without HLSL support (Beoran)
Minor formatting
Fix legacy card support when using programmable pipeline (primitives)
Use only one buffer for legacy vertices, optimize case where vertices don't need to be converted (primitives)
Explicitly refer users of the bitmap drawing functions to the documentation of al_draw_bitmap for the note about restrictions on the source bitmap
Don't restrict typing in the JS search.

It's a bit confusing to find yourself unable to type invalid strings... seems
better to allow it and just show nothing.