New mode

Hi @febuiles, it' s been a while since I wanted to share these changes. Basically I defined a formal lyricwiki-mode for our lyrics buffers instead of using the plain special-mode. Also added a few key bindings to allow calling `lyrics' and `lyrics-manual'  from the keyboard and to allow killing the buffer without prompting for confirmation. Another thing is that I moved all the symbol names into the `lyricwiki/' namespace. Finally added fontification to the song title. Let me know what you think. Have a good one!