Added modulo operator '%'

- added OP_MOD, which performs a modulo operation on the 2 <number> values on the stack. Pops the 2 values and pushes the result.
- also added TOKEN_PERCENT to the lexer, and extended binary() in cparse.c to support it.

src/cdebug.c

@@ -144,6 +144,8 @@ int disasmInstr(CChunk *chunk, int offset, int indent) {
             return simpleInstruction("OP_MULT", offset);
         case OP_DIV:
             return simpleInstruction("OP_DIV", offset);
+        case OP_MOD:
+            return simpleInstruction("OP_MOD", offset);
         case OP_TRUE:
             return simpleInstruction("OP_TRUE", offset);
         case OP_FALSE: