ignore commented lignes when looking for translatable strings
add BuildToolbar function

will be used by PictureBrowser
small changes to autoselpicture and add $Image_ext_re
various tiny fixes and improvements
add lots of features to PictureBrowser

- zoom and dragging of the picture
- fullscreen mode
- optional file and folder lists
- optional toolbar
- easy to add pictures by dropping files and url
- pdf support
- can delete or rename files
- can be used to select the picture of the current album
- can open picture in new window
add support for animated images in PictureBrowser

probably not very useful, but it is fun to add :)
fix warning with SongInfo title in default layout

and fix the layout to use the song_info page and not directly the SongInfo widget