Revert "Don't bother with the forced placements.  The "missing" loop will"

This reverts commit 1bf982939f6ede8219b6a6a0fda718eaaf7130e8.

Conflicts:
	sudoku.rb
Remove inadvertent copy of the "eliminating" loop.
Change the order in which the strategies are applied to make it
more human-like.  But not very.