don't erase the old listing until the new one is ready.
new assembler drop.
when an interrupt occurs, jump to the new PC before returning from step(), so that the ui can be updated. we still need to check at the top of the function, too, in case an interrupt happened outside.
fix save.
update demo for new assembler features.
add C-S-a for matt, fix a fractional-pixel em bug greg found, and fix copy/paste a bit more.
new drop of d16bunny
hook up syntax highlighting!
use diamond for alt.
add Congeal.
can save and load session!