Introduced MultipleToEnumerableRelay,

which will provide an alternative handling of MultipleRequest, relaying
that request to a request for a corresponding IEnumerable.
Refused irrelevant requests.
Handled direct request for multiple.
Handled MultipleRequest of non-type requests.
Handled seeded multiple requests.
Extracted a helper method,

hopefully in order to make the code more readable. You may think it was
more readable before, but I was concerned about the reversal of null
checks: some of the null checks were checking for null, whereas others
were checking for 'not null'. I was concerned that a casual reader might
not notice this (because I actually made that mistake while implementing).
Introduced MapCreateManyToEnumerable

as a customization that will apply MultipleToEnumerableRelay to a Fixture.
Implemented MapCreateManyToEnumerable.
Added a Null Guard.
Added another Null Guard.
Demonstrated that CreateMany can be relayed

to IEnumerable.
Added XML documentation.
Incremented minor version,

in order to indicate that the addition of MapCreateManyToEnumerable is a
new feature (resolving #128).