[Coco] NitrOS9 clock modules

[Bob Devries]

Hello Tormod (and others),

I don't think there's a need for a 50hz and 60hz clock module in Level2. 
There's no difference even at source level.

This code in clock.asm checks for 50Hz operation:

* Note: this code can go away once we have a rel_50hz
IFEQ TkPerSec-50
ldb <D.VIDMD get video mode register copy
orb #$08 set 50 Hz VSYNC bit
stb <D.VIDMD save video mode register copy
stb >$FF98 set 50 Hz VSYNC
ENDC

Since we indeed *do* have a 50Hz REL module, maybe that code is now 
redundant?

Regards, Bob Devries
Dalby, QLD, Australia