Merge branch 'release/v0.3.0' into development

* release/v0.3.0:
  preparing The Big Cleanup Release v0.3.0
  docu: embedding the new examples in the docu
  examples: vanderpol: moved to examples namespace
  examples: scalar: moved to examples namespace
  examples: advec-diff: moved to examples namespace
  docu: don't generate documentation for Easylogging++
  again fixing compiler warnings (this time: sign-compare)
  again fixing compiler warnings (this time: unused functions)
  again fixing compiler warnings (this time: )nused variables)
  fixing some compiler warnings (finally)
  docu: update and prepare changelog for upcoming release v0.3.0

Signed-off-by: Torbjörn Klatt <t.klatt@fz-juelich.de>