Weapon FR: type5 beam sequence expansion

Isolated and salvaged from #2412 now that most of that request is effectively implemented
How it works now: A type 5 beam can step through a pattern of angle changes, defined as a comma separated list of angles. A negative value in this list will make a purely random rotation step.

There are some things I think could be added to this system that would make it even more versatile. I'm given to understand that some similar functionality exists in parts of the modern particle system, but I have not investigated that deeply.

RANGES:
Instead of a single value, allow entries to be a further-parenthetically enclosed pair of values to define a range for that step. This would need to accept negative angles as actual angles, as the difference between (-30,30) and (330,30) is potentially pretty significant, though I suppose if it was aware enough of order that could take care of that too.

RANDOMIZED SEQUENCE

Like sound set syntax, allow a beam to be flagged as random rather than sequential. For instance if you had a beam that was (0,90,180,270) then every shot would start at one of those four angles at random. If you had a beam that was (15,30,45) then each shot would continue to progress in the same direction but at an unsteady rate. This could be done with ranges too but this way opens up options for interesting patterns to the steps and potential weighting. And then something like (10,10,10,10,370) would let you have a beam that usually steps forward but sometimes steps back. Combining with ranges could let someone get quite sophisticated with their behavior./