This intentionally will not build without --enable-ffmpeg for now.
We add new functions to the RenderAPI called AVI_Think and AVI_SetParm. Game
developer is supposed to call AVI_Think each frame and set video playback
parameters through AVI_SetParm function.
What's tested:
* Intro cinematics.
* Looping videos.
* Playing back an hour long video.
* API extension (PrimeXT's avi branch at https://github.com/a1batross/PrimeXT).
What's broken:
* There is no way to seek a video file, only rewind to the start.
The `.editorconfig` file in this repo is configured to trim all trailing
whitespace regardless of whether the line is modified.
Trims all trailing whitespace in the repository to make the codebase easier
to work with in editors that respect `.editorconfig`.
`git blame` becomes less useful on these lines but it already isn't very useful.
Commands:
```
find . -type f -name '*.h' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
find . -type f -name '*.c' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
```
