Don't bob when riding a conveyor.
Don't allow non zero tags on Boom generic doors.

I originally thought that it would be a good idea to allow for tag 0 or non-zero in a single place. This fails with Boom generic doors as the tag is used to control the lighing level. So a bodge upon a bodge...
Allowed maps to be patched when loaded.

Although no longer actually needed as the previous commit corrected the underlying problem.