Ability to reference another validation

[stramel]

It would be nice to be able to reference another validation.

Something like:

password: t.applyCascade(t.isString(), [t.matchesRegex()]),
repeatPassword: t.applyCascade(t.isString(), [t.isOneOf(t.ref('password'))]),
//or
repeatPassword: t.applyCascade(t.isString(), [t.matchesRef('password')]),