Offline version update

In version 20 of the offline mod, we fixed a whole bunch of issues, as well as added some smaller features:

• Fixed enemy Artillery not being able to attack you

• Fixed enemy spawn timers resetting when you leave the game

• Fixed some stuff behind the scenes for certain upcoming units

• Fixed UI elements not being shown on their right place. Scaling is still broken, we're aware of this.

• Fixed settings window not opening (thanks @neyn)

• Added Fog of War as an option in the settings. We're aware of visual glitches when using this.

• Added white borders around friendly tiles (thanks @neyn once again)

• Added keybind F to enter fullscreen (messes up the UI, we're on it)

Made preparations for upcoming desert release.

We are still working on adding Desert map into the game as well, but due to the huge amount of work it requires this might still take a while (thanks @Christiaan1 for doing the most boring job ever)!