Includes following changes:

 0230d0698e59 add initial GitLab CI support
 5e13b797a988 iron out all extra compiler warnings
 802fbd4d6f39 cmake: enable extra compiler checks
 050bb5c4431b convert into CMake project
 5b350e42d1fd refactor into separate Git project

and converts the package build to utilize CMake.

Signed-off-by: Petr Štetiar <ynezz@true.cz>