Implemented bitwise operators using lua's bit32 library

[JammerGRG]

I had to split it into two passes because bitwise operators can occur within compound expressions.

Known remaining bugs: The test code I used had unicode characters straight in the pico lua code (i.e. not as part of string literals within quotes) which are apparently interpreted as numbers in pico-8. O_O I'm pretty sure the original code didn't handle this either though.