Use symbols for logical operations

boot/lexer.ll

@@ -107,16 +107,16 @@ false                   {
 nil                     {
                             return yy::parser::make_NIL(this->location);
                         }
-and                     {
+\&                      {
                             return yy::parser::make_AND(this->location);
                         }
 xor                     {
                             return yy::parser::make_XOR(this->location);
                         }
-or                      {
+\|                      {
                             return yy::parser::make_OR(this->location);
                         }
-not                     {
+\~                      {
                             return yy::parser::make_NOT(this->location);
                         }
 return                  {