Added binary-like operators guards

Now passing a BOP only one or zero arguments will throw a syntax error.

After that patch, doing like (= 5) would be translated to () which is not valid in Lua.

Example:

spelunker.crn:140:29
      ] (or (= "Y" i) (= "y" ) (= "N" i) (= "
                      ^^^^^^^^
Error: Operator #eq needs at least two arguments!