Merge pull request #51 from chdemko/master

Add uml graph for ArrowRelation
Merge pull request #52 from chdemko/master

Check style and uml graph for Context and ClosureSystem class
Local commit before pulling official repository
Try to merge https://github.com/kbertet/java-lattices

Conflicts:
	src/lattice/Concept.java
Clearing conflicts
Check Style for ImplicationalSystem
Add unit test for ImplicationalSystem (partially)
Update ChangeLog
Merge pull request #53 from JeanFrancoisViaud/master

Implicational System
Adding uml graph for ImplicationalSystem