Make FLAC 1.1.3 requirement warning FLAC decoder dependant.

git-svn-id: svn://daper.net/moc/trunk@2647 910807d9-36e0-0310-a014-e9ea483e2ba4
Fix duplicate playlist entries causing abort in rb_insert().

If a file appears multiple times on the command line or a playlist
containing a file appears before the file itself, then that file
gets added to the playlist multiple times.  An attempt is then made
to add the file to the rb-tree a second time when building the menu.

git-svn-id: svn://daper.net/moc/trunk@2648 910807d9-36e0-0310-a014-e9ea483e2ba4
Send error message to clients with server error events.

The server used a static buffer from which the error message had
to be retrieved via CMD_GET_ERROR after an EV_SRV_ERROR was sent.
That meant that only the latest error message was ever seen, and
if there were multiple outstanding errors then that last message
was shown multiple times.

git-svn-id: svn://daper.net/moc/trunk@2649 910807d9-36e0-0310-a014-e9ea483e2ba4
Fix event notification suppression for some client configurations.

If the client built a playlist from the command line arguments and
'SyncPlaylist' was set to 'no', then the client did not send the
server a CMD_SEND_EVENTS command.  Knowing the client did not want
events, the server did not send them when they occurred.

Unfortunately, this suppressed *all* event notifications, not just
those relating to playlists.  Therefore, the client did not know
(and could not display) the current state of the server.

git-svn-id: svn://daper.net/moc/trunk@2650 910807d9-36e0-0310-a014-e9ea483e2ba4
Note that softmixer must be enabled to provide mono-mixing.

git-svn-id: svn://daper.net/moc/trunk@2651 910807d9-36e0-0310-a014-e9ea483e2ba4
Flag unassigned key commands in the help menu.

git-svn-id: svn://daper.net/moc/trunk@2652 910807d9-36e0-0310-a014-e9ea483e2ba4