Wrapper for protocol/ArgParser.cxx.

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".