Got rid of some compiler warnings because of const POD return values. I think it is unlikely that we will ever have return types that are modifiable as rvalue, so I think we can do without that const.
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of https://github.com/HRZaheri/espresso
Merge branch 'master' of github.com:espressomd/espresso
Merge branch 'master' of github.com:espressomd/espresso
Fixed wrong file name in ug.