Almost ready for first stable release (0.0.2)

Although the number doesn't comply with semantic versioning, it is just a temporary version until we reach the first stable release.

This adds improved GUI, realtime multiplayer, and lot's of code improvements.

Note that when we say "first stable release" we mean the first release that will be playable. As in things will work, you will be able to move around the map, the game state will be saved...
Although it will still lack most of the gameplay elements.

The first really playable release will be 0.1.0, although a feature list of things that are required for that version to be considered ready is yet to be defined.