* updated travis to also build nacl and android
* looks like this doesn't work
* fixed calling configure from within Makefile
* updated SDL
* added another header image
* fixed building the tests with --enable-only-xxx
* fixed indent
* small optimization
* don't link ogg if it's not available
* fixed tests
* added some tutorial maps
* allow to specify the app to build
* updated website
* don't jump around while switching the tabs
* hide the market place buttons for the other game
* removed headline
* added sublinks and forum link
* fixed ids and tweaked css
* fixed duplicated tutorials maps in the campaign
* don't unlock the first three maps