Improve Lyrics Pane

[andreldm]

1. Possibility to show or hide
2. Set a minimum size to the lyrics pane
3. Improve the lyrics fetcher, fixing the 'Not found's and 'Error while fetching's
4. Create a lyrics table on database
5. Create a lyrics editor(changes only locally)
6. Store the music as pure text, before passing to the HelpView we add the