[new feature] Laser 500 cursor key input

[nippur72]

In Laser 500, it's more natural to use cursor arrow keys instead of IJKL.

Unfortunately Z88DK disables them by default (I will address a bugfix for that) but you can re-enable them by having the following compiler switch added to your makefile:

-pragma-define:CLIB_LASER500_SCAN_EXTRA_ROWS=1

After that, the keyboard input routine will return:

UP: 11
DOWN: 13
LEFT: 8
RIGHT: 9

that you can use in place of IJKL

[Fabrizio-Caruso]

This is going to be fixed but I would like to have it in Z88DK first. I have reported that joystick emulation through cursors is not working...