Add names for more Audio codecs

- So they don't just show up as "Etc."
Fix the building of libav after fresh clone

- Now the build script will handle initializing and updating
  the libav submodule.
Fix playback when framerate changes

- When playing FFMPEG-decoded videos if the video stream
  framerate changed there was some automatic timing
  adjustment code that would set that frame's time
  to what was "expected". This code comes from
  26c79dbf31809d71235eb5871834d5a65f5dc314
  (fixed the problem that some mkv file is played not
  smoothly after seeking). Since the commit doesn't
  really explain the problem and I'm seeing it cause
  a real problem in this case I'm deleting the code.
  If the problem described in that commit returns
  then the issue can be reevaluated taking this new
  issue into consideration.
- What would happen is that when the framerate changed
  libav would deliver a frame that was (in my case)
  slightly farther ahead in time than we expected the
  next frame to be. So we would force the frame's time
  to be what we actually expected the next frame's
  time to be and picked a new next frame time based
  on that time. This would cause frames to eventually
  get far enough out of sync that the timer adjustment
  code in the display path would see us way out of
  sync and force the clock current time to jump forward.
  This would make the video play as though it were
  being fast-forwarded.
Update project to work with new Xcode on 10.9

- Update compiler to use the default. I'm not too excited
  about this as it might cause trouble with people building
  on different versions of Xcode but trying to carry obsolete
  compilers forward seems worse. In practice I'm sure this
  will work fine.
- Set deployment target to 10.7. Not sure why I had it at 10.8
  before but whatever. I'd like to support as old as is
  practical right now and 10.7 is it for now.
- Set it to build against latest SDK since Apple is aggressive
  about removing old SDKs. Just have to be careful about using
  the right API calls.
Fix compile errors found with Xcode on 10.9

- Missing OpenGL header imports.
Specifically specify clang++ for building Matroska

- trying to use GCC was getting us mismatched standard c++
  libs which caused link in Movist.
- delete contrib/build if you're getting link errors.
Remove SDK reference from libav build script

- SDKs are always disappearing (like 10.7 is from latest
  Xcode versions). Obviously these weren't useful anyway
  since they didn't fail even though the SDK is gone.
- Also made minimum OS X version into a variable so it's
  easier to update. Would be best to piggyback on the
  Xcode setting though.
make libav build script use MACOSX_DEPLOYMENT_TARGET

- Xcode sends this down as an environment var.
- Now we only need to update this in one place to change
  the minimum version.
Fix exception for CIFilter on MMovieView

- In 10.9 and later OS X requires setLayerUsesCoreImageFilters:
  be called on any views that will have filters attached to
  their layers and will throw exception if not. Looks like
  this only happens if the binary was linked against 10.9
  (makes sense).
- Wrapped this in a guard for when running on older versions
  since we support back to 10.7 still.
Fix icon position in movie view

- I guess this has been uncentered ever since I moved to
  CALayers for the movie view. Or maybe some change in
  10.9 is exposing this just now. Either way I think
  this is how it's supposed to be.
Adds .webm extension detection for playback.
Merge pull request #31 from gradha/pr_adds_webm_detection

Adds .webm extension detection for playback.
Adds m2t extension as variant of supported files.
Merge pull request #34 from gradha/pr_adds_m2t_extension

Adds m2t extension as variant of supported files.
Don't "downmix" mono to stereo

- This fixes a playback issue with video files that have mono
  audio streams. This was causing it to copy mono audio data
  as if it was stereo which would be filled halfway with garbage
  causing nasty pulsing noise in the output and a slowed-down
  audio track (playback was still mono, only data was copied
  as if it was stereo).
Fix playlist rowheight

- The tableView:rowHeight: delegate method is supposed to
  return a CGFloat which when building 64-bit is a double
  and not a float. This caused the rows to have zero height.