Scroll annotated file (Blame) to the line(s) selected in the document

Scrolls directly to the first row in the table containing the revision, author and timestamp info of the currently selected position in the document, so you never have to search for it.

Takes multiple selected lines into account and therefore paints the position border for these as well for better visual orientation. 

Closes https://github.com/textmate/git.tmbundle/issues/8