New hexagonal button design and tutorial updates

UI Update:

- Playing around with some new hexagonal shaped buttons, to make the build UI smaller (more compact). The description is also made smaller. Right now only the turret buttons were changed, but I will quickly transform the buildings to this style soon!

Tutorial Update:

- The tutorial is almost finished, however there will be 2 new features before feature-stop and they will need to be added to the tutorial as well! These features are: ammo reloading (manually with a button) and object repairing (similarly to reloading), but they are not yet implemented.