AbstractImpl: Remove unnecessary comments
Use '==' operator

- AbstractImpl::where()
- AbstractImpl::findWhere()
- ArrayImpl::repeat()
AbstractImpl: s/self/static
Fix for DeferIterator
Makefile: Improve src/Underbar/Enumerable.php rule
Revert "Add key selector argument to map()"

This reverts commit 6e9e1af3fe92f2650990be27a58c7af7727c18fd.

Conflicts:
	src/Underbar/AbstractImpl.php
Fix comments
Implement sample()