Revert "Added Corner Black"

This reverts commit ea7ef9bb671ae4d5d5aeee2f8c710325e725d21b.
Revert "Revert "Added Corner Black""

This reverts commit 906170854ab6c422007db0844cb18ea1a99a9f27.
Updated CornerBlack

updated the corner black nurikabe rule icon
Added check for external black square in contradiction
Also, added proof that shows serious slowdown in nurikabe
Merge branch 'master' of https://github.com/Bram28/LEGUP
Linked to the new Corner Black icon

Deleted some old proofs that couldn't load anymore

Added some new proofs to show which icons still show up and which do
not.

Also added a complete proof of the one Nurikabe puzzle
Fixed justification icons not displaying after loading proof

Changed getImageName method in Justification to abstract
Implemented method in all subclasses of Justification
commit
Fixed the Fill In Black rule
trying to commit a proof ...
Created TreePanelDV class - tree panel using DynamicViewer
Renamed test and test2 to reflect their purpose
Suppressed warnings for java 7 errors where fixes would break java 6 compatibility
Partially implemented DynamicViewer-based TreePanel

Drawing doesn't yet work correctly. (Items are drawn in the wrong positions.)
Panning doesn't yet work.
Removed deprecated files, more testing code
Partially fixed tree panel visibility problems
Fixed tree panel rendering
Fixed mouse click events on tree, removed dead code