Merge pull request #10 from bekaus/master

Lpcplex now supports maximization accumulator
Create README.md
Wrong stopping condition in alpha-beta-swap (Found by Torben Kroeger)
Merge pull request #11 from joergkappes/master

Alpha-Beta-Swap : Stopping criteria was to wrong and thus stop to early 
Update README.md
Update README.md
Update README.md
added missing #include "opengm/operations/maximizer.hxx" in lpcplex.hxx
Merge pull request #12 from hanslovsky/master

fixed missing include in lpcplex.hxx
added GraphicalModel::getFunction