Fix Cypher's Operators and Add RETURN Clause Back

Cypher Operators were not being created correctly causing an error. Fix that issue and add back the RETURN stmt to the Grammar

Author: JoshInnis

regress/expected/expr.out

@@ -35,45 +35,53 @@ USE GRAPH expr;
 -- a bunch of comparison operators
 --
 RETURN 1 = 1.0;
-ERROR:  operator is not unique: postgraph.gtype = postgraph.gtype
-LINE 1: RETURN 1 = 1.0;
-                 ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN 1 > -1.0;
-ERROR:  operator is not unique: postgraph.gtype > postgraph.gtype
-LINE 1: RETURN 1 > -1.0;
-                 ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN -1.0 < 1;
-ERROR:  operator is not unique: postgraph.gtype < postgraph.gtype
-LINE 1: RETURN -1.0 < 1;
-                    ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN 'aaa' < 'z';
-ERROR:  operator is not unique: postgraph.gtype < postgraph.gtype
-LINE 1: RETURN 'aaa' < 'z';
-                     ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN 'z' > 'aaa';
-ERROR:  operator is not unique: postgraph.gtype > postgraph.gtype
-LINE 1: RETURN 'z' > 'aaa';
-                   ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN false = false;
-ERROR:  operator is not unique: postgraph.gtype = postgraph.gtype
-LINE 1: RETURN false = false;
-                     ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN ('string' < true);
-ERROR:  operator is not unique: postgraph.gtype < postgraph.gtype
-LINE 1: RETURN ('string' < true);
-                         ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN true < 1;
-ERROR:  operator is not unique: postgraph.gtype < postgraph.gtype
-LINE 1: RETURN true < 1;
-                    ^
-HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
+ ?column? 
+----------
+ t
+(1 row)
+
 RETURN (1 + 1.0) = (7 % 5);
  ?column? 
 ----------