Don't generate EN/ENO output

[Andrey Skvortsov]

If AND/OR/XOR/ADD/MUL are used without EN/ENO, use corresponding operator instead of function. For example, (op1 AND op2 AND op3) instead of AND(...)

matiec generates much better C code for operators, than for functions with variable number of arguments.

Original performance problem is described here: https://sourceforge.net/p/beremiz/mailman/message/36210898/