number of unused classes. Removed playlist manager from a number of
classes and replaced with the alias, channel and channel map models.
Updated playlist manager to no longer retain a playlist except for when
loading to models or when storing from models. Extracted version 1 to
version 2 playlist conversion and changed playlist manager to keep the
original version 1 playlist and create a new version 2 (playlist_v2.xml)
file. On startup, try to load a v2, and if not, look for a v1 to
convert. Otherwise, don't create a playlist and one will be created
once the user adds items to the models.
