feature request: add `-trimtype` option to remove prefixes that match the name of the type

It's quite common to have enums that are prefixed with the type e.g.

```
type Pill int

const (
	PillPlacebo Pill = iota
	PillAspirin
	PillIbuprofen
	PillParacetamol
)
```

It would be great to have a flag like `-trimtype` that will trim the type from the value automatically, rather than having to have a long list of prefixes inside `-trimprefix`.

I'd be happy to implement this if it's accepted.