Added keyboard shortcut for small caps text (Ctrl+L, Ctrl+S)

[morgil]

Well, I often need to write small caps text, so I wrote a shortcut for this and want give it to the community. I propose Ctrl+L, Ctrl+S.

[r-stein]

Everything looks fine, but I am hesitating a little bit with adding additional C-l keybindings. Some day we may want to use that for something else.

[igreil]

Perhaps not the most pressing issue, but can we review this issue? Unless I am missing something, this is still not an option, and writing \textsc{ ... } by hand every time becomes old, fast.