Lot of improvements (vdc101 demo works).
Lot of improvements (vdc101 demo works).

- screen height now is automatically set (no more slider)
- improved xscrolling
- improved vertical sync handling
- improved line timings
- vdc101 demo now works: some minor hacks to avoid screen auto resize
- the screen width has been changed in order to remove a fixed border, both on the left and right side
- to do: vertical border to be removed
- to do: handling of regs 34 & 35; it's not clear which is the offset position

abbruzze/kernal64,abbruzze/kernal64,abbruzze/kernal64