This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Move to TagSettings.c and use C99 initializers.

For TAG_NUM_OF_ITEM_TYPES.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

Renamed functions and variables.