Super Enums

Add enums with super powers!

1. Enums with string values.
```dart
enum {
    a = "Hello",
    b = "Allo",
    c = "Bonjour",
} example;
```

2. Enums with int values.
```dart
enum {
    a = 0,
    b = 500,
    c = 600,
} example;
```

3. Enums with constructors.
```dart
enum {
    String(String),
    Bool(bool),
} example;
```
