[stringtemplate-interest] caching getter lookup speedup

[Terence Parr]

ok, added benchmarking code to v4.  Tested speed with and w/o Method/Field caching.  about 10x improvement.  Average units of work went from 32.77 to 395.22. This is a micro benchmark for property lookup.

timeSimplePropsOfArgs  :   395.24  402.13  399.98  369.82  408.94 =   395.22 units of work / ms

timeSimplePropsOfArgs  :    32.63   32.74   32.68   32.95   32.83 =    32.77 units of work / ms

Now I'm optimizing local attribute (arg) access.  Sam Harwell will be happy :)  I'll check those numbers after impl.

Ter