About all CONIO functions offering a <...>xy variant call
popa
_gotoxy
By providing an internal gotoxy variant that starts with a popa all those CONIO function can be shortened by 3 bytes. As soon as program calls more than one CONIO function this means an overall code size reduction.
Adjusted comment formatting in several assembler files.
Removed dummy kbhit() function, as it's better to get a linker
error than an implementation that does the wrong thing.