Set paramater order on sort-related routines so that the vector being
sorted/searched/etc. is always first.
Fix order of nans2end.
Allow function arguments as first paramter of sort functions
Sort updates:

* Add sort versions which take Functions as first argument,
  for use with "sort(x) do a..." syntax
* Added (but commented out) select and selectby functions
  for same.
Minor updates.
Fix sort versions which take a function as the first parameter.
Actually make taking a function argument work...
Finish cleanup of allowing function arguments first.

* Added (but did not export) selectby, sortpermby
* select, selectby, and sortpermby can take function arguments first
* Added basic tests
Merge branch 'kmsquire-sort_param_order'

Conflicts:
	test/sorting.jl