cosmetics.

Fix some segfaults by disabling functions.
Slower, faster are on the side of the slider now.

 - Don't use the .ui, do all by hand :)
 - Use a ControlWidgets to design all the controls, and implement the functions
 - Change a bit the advanced widget, that must be integrated in the
   controlsWidget
There is a lot of Not Yet Implemented, so feel free to add some.

Redesign the label & edits placement to resize the dialog

glx: fixed startup crash, which seems to be triggered by an x.org optimization, the GLX module seems to be loaded when it is queried upon, and released when the display is closed. Therefore, checking for GLX with a temporary display and using GLX apis with another will crash it.

Adds CONFIG_ITEM_PASSWORD for showing stars in preferences dialog (still to be implemented in interfaces)

* Allow getting album art for items which aren't playing (using /art?id=<the playlist id> instead of /art). (You need to run with --album-art 2 if you want to have album art for items which haven't already played)
* Workarround a stupid assert in input_GetItem.

Ogg/flac doesn't work (yet)

Fix playlist_item_t.i_id vs input_item_t.i_id mess in HTTP interface. (Looks like this was new in 0.9.0. Having 2 differents integer ids, one being used to play and the other needed to delete the item is kind of awkward.)

Second try, show save meta button if user changes any input field, also
then set in_edit=true so playlist changes doesn't change meta-data what
to edit.

- Add rtcp boolean to emit RTCP SR