Added Pause function!

Ctrl+Space can now pause and unpause your conversion!

Other changes:

• VP9 now uses VBR mode stead of CQ mode with rate limit.
• Tweaked some options behind the scenes.
• Fixed old bugs, most certainly introduced some new ones.

v0.8-a2 Merge 2 first two audio tracks, QoL changes.

Since this program was designed with the idea to share game clips on discord, having a clip with 2 audio tracks, one for game audio and one for your own mic, a new option to merge the 2 first audio streams has been added as a checkbox.

Still Alpha: All audio channels should be included.

Setup a format system, for multiple types of encodes. Not properly tested yet.

Alpha release

Description next release.
Not intended for public use. Make an issue if you want to test it. (or test at your own will/risk, but you might get confused or run into trouble, feel free to ask in that case.)