Added more details about how the CBM exec() works.
Merge pull request #35 from greg-king5/cbm-chain

Added more comments to CBM exec().
Don't shift in an unknown carry bit.

If that bit happenned to be set, then it would defeat the fancy ADC shifter.
remove ZP_CIOV_save and ZP_SIOV_save
Added a cbm510 lightpen driver.

It's similar to the current c64 and c128 lightpen drivers.
Made mousetest.c know that the CBM510 has a lightpen driver.
Merge pull request #36 from greg-king5/cbm2

Fixed a small bug in a joystick-mouse driver.
Renamed the CBM510 lightpen driver to include the 184-C pen.
Merge pull request #37 from greg-king5/lightpen

CBM510 lightpen driver
Merge remote-tracking branch 'upstream/master'