Move SMPTE handling to agi::vfr::Framerate to get all of the interesting
logic dealing with timcodes in one place, and to make it testable.
Completely rewrite the SMPTE time conversions as testing them reveals
that they were incorrect in some cases.
Originally committed to SVN as r6631.
Consistently use the C++ names for headers rather than a combination of the
C and C++ names.
Remove empty LAGI_PRE blocks.
Remove checks for both AGI_PRE and LAGI_PRE and change a check for only
AGI_PRE to LAGI_PRE.
Originally committed to SVN as r5516.
Kill vfr.h and vfr.cpp and use the libaegisub versions of them instead.
Rather than the globals VFR_Input and VFR_Output, everything related to
frame rate is now part of the video context. Most things which used to
use VFR_Output now call VideoContext::TimeAtFrame etc.; video providers,
rather than modifying VFR_Input directly, now have getters for their
frame rates which VideoContext calls. Read-only public access to
VFR_Input and VFR_Output are still provided (hopefully temporarily) for
a few things which were awkward to do through VideoContext.
The Avisynth provider now might correctly handle VFR MKVs which can be
opened with DirectShowSource but not DSS2.
Rework keyframe handling as well, so that it continues to match the vfr
handling in design and implementation.
Originally committed to SVN as r4662.
Thomas Goyne