Revert "Merge branch 'michaeleisel-permutations'"

This reverts commit a1903f70e26da2c92cdd3814e017a42a0c247e22, reversing
changes made to f531465bb8706630edf60b4a9a5e9b79e9354e3c.

Conflicts:
	ExSwift/Array.swift
	ExSwiftTests/ExSwiftArrayTests.swift
Merge branch 'revert/permutations'