[Rust] add enum members to indexed symbol list (sublimehq#4182)

* [Rust] add enum members to indexed symbol list

- to support Goto Definition etc.

* [Rust] improvements from PR review

Author: keith-hall

Rust/Symbol List.tmPreferences

@@ -9,7 +9,8 @@
 		entity.name.module.rust,
 		entity.name.struct.rust,
 		entity.name.trait.rust,
-		entity.name.union.rust
+		entity.name.union.rust,
+		meta.enum.rust storage.type - meta.struct
 	</string>
 	<key>settings</key>
 	<dict>

Rust/tests/symbols/syntax_test_symbols.rs

@@ -30,3 +30,16 @@ type MyType;
 
 union Union {}
 //    @@@@@ definition
+
+
+enum AnotherEnum {
+//   @@@@@@@@@@@ definition
+    Foo,
+//  @@@ definition
+    Bar {
+//  @@@ definition
+        toggle: bool,
+    },
+    Baz(MyEnum),
+//  @@@ definition
+}