Added comment support.
The correct color is now used as well.
The one caveat compareed to the animated gifs and that is that a multiline
selection will create one comment, not several. @markguinn said that
multiline comments do work but I have not tried it myself. If it does not it
puts us in somewhat of a bind since IDEA only defines two different comment
types, namely singleline and block. Singleline is prefix only so we can't
use that. We now have a block comment defined with the correct prefix and
suffix and this will trigger if you press the shortcut for single line
comment.
Closes #17.