Merge pull request #2 from opengm/RC2.1

Rc2.1
update Label and IndexTypes
Merge branch 'RC2.1' of github.com:homul/opengm into RC2.1
Merge pull request #3 from opengm/RC2.1

Rc2.1
Merge branch 'RC2.1' of github.com:homul/opengm into RC2.1
Merge pull request #80 from homul/RC2.1

Rc2.1