Adds selected comment folding functionality

[mrz5018]

Selected comment folding, "ctrl+alt+c", can now be used to just fold comments that are currently selected (either the cursor is within the comment or a portion of the comment is selected).

The intialization of self.comments was changed so append could be used in the new method for finding selected comments. I don't think that anything else relied upon this, but I thought it was worth noting. Beyond that some of the functions were taken out of the init routine just because they weren't common anymore.

[Exadra37]

Is this package not maintained anymore?

I would love to see this feature merged :)