Commodore 64, Commodore VIC20 and Sinclair ZX81 Emulation

This release fces some problems of the previous one, and now the simulation is almost perfect even at clock cycle level.
Many professional demos work properly!

C64, VIC20 and ZX81 Emulation

This release emulates pretty well the Commodore 64. Even at clock level.
VIC20 is also emulated, although more improvement (in accuracy) are still needed.
ZX81 is also emulated but some games the sinchonization between CPU and beam raster is not fully aligned.