Re: iee - Icon expression evaluator

I've uploaded a new version, with the following improvements:

1) Added a new reserved word, 'quit' which quits the current
expression.

2) 'clear' invoked in the middle of an expression does not clear the
current expression.

3) 'Expression not enclosed' error handling does not clear the current
expression, just the line in which the error occurred.

4) Checks for a valid procedure name in procedure declarations, and
clears erroneous entries.