`lowerThanBound()` was renamed to:
- draw attention to its corner cases
- make its single usage less cryptic
We may want to reserve the pretty name for
a function that, for example, returns `true`
if `argument` suits all the bounds.
Similarly, `canHaveSubtypes()`
does some questionable logic in case of
`INVARIANTxINVARIANT`: some hypothetical
`Inv<Foo>` doesn't have subtypes so
checking "Foo has subtypes strictly above
Nothing || Foo has supertypes strictly below
the parameter bounds" doesn't seem correct.
`Foo` may have some, but `Inv<them>` are
not related to `Inv<Foo>`.
Nikolay Lunyak
a19994b8b6