add test target to cmake and enable in travis
fix some build warnings
add sdl include dir properly
backward compatibility
update config format to version 4
Merge pull request #240 from carstene1ns/cmake_tests

add test target to cmake and enable in travis
Merge pull request #241 from carstene1ns/master

add travis badge and explicitely mention sdl version
Merge pull request #242 from carstene1ns/fix_warnings

Fix some warnings
Fix some clang warnings

Remove ConfigSaveOld
Fix config_test