Fix wx compilation and silence a warning when compiling wx
Switch to the official FFMS2 git repo now that there is one
Switch git submodules to git:// rather than ssh

Fetching stuff via ssh requires a Github account.
Bump ffmpeg and boost versions
Zoom into the mouse's position in the audio display

Rather than pinning the time at the center of the audio display, pin the
time at the mouse's position since that's the area the user probably
cares about. If the mouse is not over the audio display (such as if the
user is adjusting the zoom via the sliders rather than the mouse wheel),
just use the center as it used to.
Revert "Don't invert horizontal scroll on the audio display on OS X"

This has been fixed upstream.