fix bug about not support more operations on string (#21)

Author: studyzy

.gitignore

@@ -0,0 +1,2 @@
+.idea
+goconst

tests/main.go

@@ -27,7 +27,12 @@ func testCase() string {
 	case "moo":
 		return ""
 	}
-	return "foo"
+
+	test2 := "moo" + fmt.Sprintf("%d", testInt())
+	if test2 > "foo" {
+		test2 += "foo"
+	}
+	return "foo" + test2
 }
 
 func testInt() int {

visitor.go

@@ -62,10 +62,6 @@ func (v *treeVisitor) Visit(node ast.Node) ast.Visitor {
 
 	// if foo == "moo"
 	case *ast.BinaryExpr:
-		if t.Op != token.EQL && t.Op != token.NEQ {
-			return v
-		}
-
 		var lit *ast.BasicLit
 		var ok bool