Maintenance release.

v1.1 (18.07.2021)
* Fixed writes to POTGO: OUTLX and DATLX were set to 1; POTGO is now managed properly by means of potgo.resource.
* Fixed graphical glitches in information screens on unexpanded machines.
* Added controls information to pause screen.
* Replaced raster beam Y reading procedure with faster and interrupt-proof machine code routine.
* Made a tiny optimization.
* Improved manual.