* Make non-string ValueScanner types work with enum fields
This change fixes#1575 which now makes it possible to specify a GoType
for an enum that is not a string alias. It requires that if the specified
type is not a string alias, the type must satisfy the Stringer interface.
* remove default, rename field
* wip
* remove comment
* go generate
* make optional
* generate 🤦
* handle NULL case
* turns out mysql stores strings as []uint8