Implement a "bulk" edit mode that postpones both UpdateQueuedSong()
and OnModified().  This way, the playlist version gets incremented
only once.  More importantly: when adding multiple songs to a queue
that consists of only one song, the first song that got added will
always be played next.  By postponing this choice, all newly added
songs get a chance to become the next song.  Fixes the second (and
last) part of Mantis ticket 0004005.

Fixes assertion failure.

The string "base" is understood by locate_parse_type(), but not by
listAllUniqueTags().  The special tag type LOCATE_TAG_BASE_TYPE causes
a crash in PrintUniqueTag().

Lists files and directories.  Supports storage plugins.

Use Storage::MapUTF8() internally, don't use global variables.

Move from db/DatabaseGlue.cxx, eliminating global variable.

Reduce global variable usage, move to frontend code.

This reverts commit a577944a.

Will be replaced by new options for the old commands "search" and
"find".

Publish the Client API, preparing to move more code into the Client
class.

Replaces GLib's GError.

playlist and player_control are deprecated.

Don't use the global variable "g_playlist".