v1.25

• math: added um/mod, */, */mod
• loops: added do, loop, +loop, i, j
• interpreter: make key up recall previous line entered
• bugfixed r@
• dropped "not" word - replaced by 0=
• rearranged zeropage usage so that parameter stack is a bit bigger
• documented layout of forth words
• bugfixed docs: invert, not "not", flips all bits
• added "bl" word (for space)