Enhance rotate and zoom UI

[CrafterSvK]

Hello, I've been trying to get a hold of the codebase, so I've chosen the simplest thing I could think of.

• [x] Zooming in and out using buttons and mouse
• [x] Rotation
• [x] Zoom buttons should be disabled on min/max zoom

Rotation is currently handled by multiple keyboard input handlers which do separately things (rotate camera, rotate isometric objects). Need to merge to one keyboard handler which sends signals to other handlers. In my opinion it would be lazy to solve this by making a global emitter, for these kinds of things, maybe that's right, I do not know. Or just make button to click rotate_left, rotate_right key :)

[CrafterSvK]

Every WorldThing can now react to rotation of camera. Maybe the emit to Global camera rotation from buttons can be directly made in TabWidget so there will be no need to signal it through PlayerHUD to CameraControls.

[CrafterSvK]

Buttons are now disabled on max/min zoom. It's handled using Global singleton, maybe refactoring to different Singleton would be better. Or if you find another way to do this, I would be glad.

[CrafterSvK]

@artism90 check it out if you've got time

[CrafterSvK]

I addressed the issues, thanks

[LinuxDonald]

@CrafterSvK have you maybe time to get this pr done please?

[LinuxDonald]

@CrafterSvK how it looks on this pr?

[CrafterSvK]

Hello, I can take a look this evening. This probably will need a rebase first.