Prefer more common enumerable method names

We had historically favored the `*ect` enumerable methods (`select`,
`detect`, `inject`, `collect`) because, uh, they rhymed. At some point
we changed to preferring `map` over collect and now it's time to finish
the job.

`find`, `find_all`, and `reduce` are all available in Ruby and those
names are more consistent with other languages.  They also have the
advantage of sounding distinct from the previous method names
which makes them easier to differentiate for people new to them.