Presets save a complete set of directory assignments for the source tabs
(Song, VoiceTrack, Jingle, Drop, Opener, Promo, Contributions).

A preset also stores the currently open playlist.
This allows switching quickly between different show configurations.

The 'Preset' tab (Shift+F3) shows all saved presets in a tree structure.

Sub-chapters: Load Preset, Save Preset.
