more ShockScript optimization--now 10x faster!!

Well, I once again got into the guts of ShockScript and made some strictly under-the-hood changes. Mostly I greatly reduced the usage of untyped variables (which are slower than strictly typed ones).

The result is a 10x speedup, at least in some cases (could be higher or lower in others, I have not done extensive benchmarking yet). Specifically a dumb loop that iterated 20,000 times and set a variable on each iteration took about 1.1 seconds on the pre-optimization ShockScript; it now takes about 0.12 seconds.

I still have some glitches to work out (not all of my ShockScript code compiles without errors yet) but simple examples work fine with a great speedup.