Merge pull request #8 from marc-hanheide/master

Refactoring and catkinising of simulation to support multiple environments more transparently

WARNING: There are currently no launch files for the 2D navigation in simulation! That is, if you don't need the new repository structure by now, please wait until the launch files are in place.
Merge branch 'master' of github.com:strands-project/strands_morse into topic-relay