For nonzero values we were leaving Z=prev, which is wrong when Z=0
because the AND result might be zero. Now if Z=1 we leave it alone,
but if Z=0 we now set it to Z=?.
Test 1003-flags-and-branches was testing for the (incorrect)
behavior, so we're now running into a BRK. This is fine.
Added a blank line after local variable tables. Otherwise they
just sort of blend in with the stuff around them.
Put prefixes before the DOS 3.3 platform symbols.
Added a BAS_HBASH entry. We were getting BAS_HBASL and MON_GBASH
paired up, which looks weird.
Apply a very light tint to the preview section of the Edit Long
Comment dialog, to hint that the window is read-only.
