Amiga Mouse in Port 1 blocks core's keyboard

[sy2002]

As reported here:

https://www.forum64.de/index.php?thread/125676-c64-core-f%C3%BCr-den-mega65/&postID=2154516#post2155129

An Amiga Mouse in Port 1 blocks (probably) any core's keyboard. Tested with C64 and ZXUno.

TODO:

1. The MEGA65 core does not have this problem and I do know that in the VHDL codebase of the MEGA65 core there is code that handles the Amiga mouse and even can detect it. We should use that tp prevent that this happens.

2. Update the C64 FAQ before we release 5.1 (this will be tracked in the C64 issue tracker, here: Documentation TODOs for Release 5.1 MJoergen/C64MEGA65#123)