gazebo is marked for autoremoval from testing

[Debian testing autoremoval watch]

gazebo 7.3.1+dfsg-3 is marked for autoremoval from testing on 2017-02-11

It (build-)depends on packages with these RC bugs:
849696: libogre-1.9.0v5: Ogre games abort on startup with “basic_string::_M_construct null not valid”