Previously visualSubToolBar has boarder while visualToolBar does not. So the width of the toolbar will change when toggling visualSubToolBar.
Now we remove the boarder so they have the same width. A separator is added at the top of visualToolBar instead to provide visual cue.
Fixwangqr/Aegisub#11
It's modestly faster, significantly more type-safe, and doesn't assert
when there's too few arguments, which causes problems for plural forms.
Closes#1733.
Add a new Project class which is responsible for everything related to
opening and closing audio, video, subtitles, timecodes and keyframes.
This pulls almost everything not directly related to playing audio/video
out of the audio and video controllers, pulls more crap out of
FrameMain, and happens to make things a little simpler in the process.
wangqr