COMPIL (edit 471) enhancement: four new shortcut operators defined:
var += <expr> ! equivalent to var = var + (<expr>)
var -= <expr> ! equivalent to var = var - (<expr>)
var *= <expr> ! equivalent to var = var * (<expr>)
var /= <expr> ! equivalent to var = var / (<expr>)
These require /X:2 or /RC, but they do not have any compatibility effect on the resulting RUN module.
