Literals on byte reciving mnemonics don't work

[schtrudl]

Consider

LDCH =4

that gets assembled to:

LDCH f
f WORD 4

but that doesn't as MSB is 0. The solution is to either emit BYTE:

LDCH f
f BYTE 4

or:

	LDCH f
f	WORD 4
f2	EQU f+2

(because LDCH f+2 does not work).

All device mnemonics are affected too.