Implement/review Docker support for CI #57
Description
Currently the game can be built on machines that have all prerequisites installed. However, prerequisites may change quite often and the build scripts on automated build servers can get outdated pretty fast. Aside from this, many operating systems and environments like Debian or Ubuntu often don't provide the required packages in their repositories, or the versions they provide are outdated.
By using Docker to build the game on those machines it is possible to provide an isolated environment that is definitely able to build the game and can be tested locally, as well as update those build scripts when needed. Such process is also more resistant to any failures, ensuring no garbage is left after a failed build.