Forth500 v2.0

• increased colon call-return execution speed by 20%, using yi and zi 20 bit address registers with a fixed 11th segment: this optimizes all 16 to 20 bit address conversions by moving a 16 bit address through yi or zi to obtain a 20 bit address
• increased execution speed of single and double integer literals, variables, values, constants, single and double integer store and fetch, single integer arithmetic involving addition and subtraction, and single and double integer stack operations
• fixed MOVE when source and destination address are equal
• added RUN and PRO display annunciators: RUN lights up when interpreting and PRO lights up when compiling from the prompt
• changed WORDS to no longer display inaccessible smudged (hidden) words (e.g. when their definition failed to compile)
• changed FENCE to a value instead of a variable
• added FORTH, VOCABULARY, DEFINITIONS, CURRENT and CONTEXT words
• corrected minor errors and omissions in the manual
• included several new examples and additions to Forth500/additions