Beta version 4; UI improvements

Finally, beta version 4 is here. It features a bunch of UI improvements, based on the suggestions and feedback.

All the hotkeys are now configurable, and more of the UI parameters can be adjusted according to ones taste. The player is given more information in a better organized way.

Feel free to keep on posting bug reports, questions, suggestions and any other feedback. UI-related wishes are welcome, although for the coming few weeks the development focus will be on adding more game content and polishing some of the existing mechanics.