Bugfix/replace vga connector (#20)

* Starting to replace VGA connector.

The Amphenol connectors used on Monotron and the Neotron 32 have a
roughly 8.5mm offset to the board edge. Fixing this will involve moving
a lot of stuff.

* Finish adding new VGA connector.

Had to bunch up the R2R DACs a bit, but overall
it seems tidier this time!

Author: thejpster