Moved some documentation, added wallsIdentified to the Cell in Floodfill
Merge remote-tracking branch 'upstream/master'
Revert "Merge remote-tracking branch 'upstream/master'"
Fixing my hasty merge, before I was ready.  Will commit again soon.

This reverts commit 6b8e9003f026e0be8d8d0869b9f91c0282aac570, reversing
changes made to 8999e3c195c4d814a037daf44ded24f93c346e59.
Incorporated Mack's changes (see his recent commits).