make apply_along_axis public and have it return a projection

cleanup
more cleanup, but also note that the previous commit renamed
"apply_along_axis" to "apply_function", which is more accurate
fix test: unnecessary comma added
fix return type from _apply_numpy_function.   Now that I think about it,
that should probably be made public too
make apply_numpy_function public and have sum, min, max return
projections by default

forgot an underscore

whitespace
make callspec of apply_function and apply_numpy_function same
added changelog entry
fix bug: this was introduced when branches were switched and data was
discarded, which I've never seen before
add documentation, remove locals() reference
out is None check
sum, max, min should not return projections if naxis is not a single
integer
Merge pull request #100 from keflavich/apply_publicly

Allow "apply_function" as a public function