configure.ac: Don't call AC_C_CONST - C compilers without 'const'
support haven't been relevant for years.
src/msvc/config.h.in: Update to INT16_T to int16_t and INT32_T to
int32_t.  AFAIK, building with MSVC hasn't been tested for a long
time, so it's likely more fixes will be needed.
src/img.c: In non-hosted mode, check that int is at least 32 bits,
and if not, use long.  In practice, platforms with 16 bit int are
mostly obsolete, but it's not hard to be portable here.
src/moviemaker.cc: Fix GCC warnings.
src/moviemaker.cc: Set rc_buffer_size to avoid warning from libav
when exporting MPEG.
doc/cavern.sgml: Document --3d-version in cavern man page.
src/Makefile.am,src/imgtest.c: Add compile test that img.c and img.h
work in non-hosted mode.
src/img.c: In non-hosted mode, don't define GETC and PUTC if they're
already defined, to allow easy overriding with getc_unlocked() and
putc_unlocked().
lib/: Add "Language:" headers to .po files.
NEWS,configure.ac: Update for 1.2.9.
doc/HACKING.htm: Document how to configure wxWidgets 3.0.0 for mingw
cross-build.
Preserve INSTALL when running autoreconf
Use wxWidgets 3.0.0 install for MSW build
Create and upload detached ascii-armoured GPG signatures