Code review comment for lp:~widelands-dev/widelands/per-level-soldier-anims

This operator doesn´t have any meaning, level ranges do not have a logical order. This is here only because the compiler printed lots of errors caused by std::map et al that referred to missing comparability and assignability, so I made this mockup to get rid of those. Travis still seems unhappy though, I´m not really familiar with certain peculiarities of C++…