Add trap for divide by zero in expression library Added a trap for division by zero in the expression library and adjusted lwasm to use it and report division by zero errors instead of crashing with a cryptic "arithmetic exception" or even more mysterious "floating point exception".

\.exe$
\.o$
\.d$
\.a$
~$
\.orig$
/lwbasic$
/lwlink$
/lwobjdump$
/lwar$
/lwasm$
/lwcc/lwcc$
/lwcc/lwcpp$