More syntax changes!

* Comments changed to back-ticks -- the slashes were just too heavy and
I disliked greatly having two characters for a common comment marker
* Added PARAMS to PROCs -- a means of documenting procedure parameters
and return values
* Added some preliminary stuff on bit flags -- this is going to be an
area where OZ80 blows other assemblers out of the water...
* Added some string escape sequences. Need to think about `/r` vs `/n`
&c.