OSWRCH improvement ideas

[Tom Seddon]

Squeeze out a bit more speed in the common case. In my quick test of LISTing a 200-odd line BASIC program, the LIST took 0.95 the time. Insert before this line:

acorn_mos_disassembly/src/mos.s65

Line 8371 in 1bcd69d

 bcs LE869 

                ; Early out when doing VDU output only.
                lda characterDestinationStatus
                beq LE8A5

[Tom Seddon]

jsr selectMOS in MOS 3.50 here that could be inlined (as per MOS 3.20):

acorn_mos_disassembly/src/mos.s65

Line 8353 in 1bcd69d

 jsr selectMOS 

[Tom Seddon]

Some pointless-looking code here:

acorn_mos_disassembly/src/mos.s65

Line 266 in 1bcd69d

 tya