Tweak Codecs

[madeinlisboa]

I noticed that Proshow uses x264. I'm comfortable with this codec and I would like to tweak it myself, instead of having to deal with the default settings. Even the audio should be configurable. Probably most of users don't need that, but some do, because the video setting used by Producer are very conservative.
The codecs ought be easily upgradeable. The x264 version of Proshow is already dated and I can't use a newer version.