There was a mistake in the JMP code which meant that one instruction at
the destination would be skipped when the jump was taken. This commit
also changes the meaning of the culprit parameter to make it less
confusing and avoid similar mistakes in the future.
The PICA200 semantics for multiplication are so that when multiplying
inf by exactly 0.0, the result is 0.0, instead of NaN, as defined by
IEEE. This is relied upon by games.
Fixes#1024 (missing OoT interface items)