static detection of array range errors

[richfitz]

We've had the bits in place for this for a while but after #139 is done it will be easier:

• go through all array accesses and find the min/max parts
• put these into the IR as constraints
• quite a few of these can be eliminated entirely statically

But we reduce the problem to a preflight check that happens at once per parameter setting action, and we might be able to remove all the "safe mode" bits after that

[richfitz]

tests removed in f689e05