Add save method to MediaFile
Move sys.stdout encoding handling to UI module
Rename 'WARNING' verbosity to 'WARN'
Add support for enabling/disabling color output
Add support for specifying UI output
Formatting
Add TrackUI write and message functionality
Add support for 'save_callbacks' on media files
Start organizing things into 'processors'
conventions: rename to 'media-conventions.md'
Update readme with detailed description of import