JBasic 1.5-6 Release

This release has three main goals.

1. Improved compatability with other dialects of BASIC, particularly in file I/O statements and in function names

2. Improved optimizer behavior for integer-intensive programs. This includes constant folding and a few new bytecodes added to handle integer-specific cases of generalized instructions.

3. Numerious bug-fixes, targeted at preventing the user from making "rookie" mistakes.