added command to automatically patch tapes for the "EM random bug"

added command to automatically patch tapes for the "EM random bug"

This adds a command line option that can be used to patch existing
tapes (by setting or unsetting property bits in the tape header).

The only patch mode currently available is "em_random_bug" that sets
the property bit for using the 64-bit random value workaround in the
EM game engine (see commit 1006b2db for details).

When using "help" for "MODE", all available patch modes will be shown.