Special resource graphs and behind the scenes improvements

While this release doesn't add many features, I completely rewrote central parts of the application. This should mean stability improvements across the board and should also allow me to add features more easily going forward.

New features:

• Graphs for special resources
• Empty graphs are no longer drawn

This update is compatible with Stellaris 2.2. As far as I can tell, it should be compatible with databases generated by version 0.3, but I am not 100% sure.

As always, all bug reports are highly appreciated! You can message me on reddit, open a github issue, or start a new discussion topic in the Steam workshop page.