*VERY* Basic UI Functionality

[Rover656]

This adds a UI engine with basic render and interact abilities. It also supports panels that allow controls to be ordered correctly.

UI Engine classes

• [x] UIControl
• [x] UIControlInteractible
• [x] UIControlSized
• [x] UIPanel
• [x] UIWidget

Included Controls

• [x] BasicButton (Label inside an interactive control, needs rework in feature/ui-advanced)
• [x] HorizontalPanel
• [x] Image (Texture element)
• [x] Label (Text element)
• [x] Vertical Panel

Other changes

• Fixed a bug in GraphicsManager which made 2+ render targets break
• Made mouse events cancellable
• VS 2017 project removed in favour of cmake
• Added support for MinGW
• Added a basic logger (doesn't write to file)

Things needing done in feature/advanced-ui

• ScrollPanel
• Separation of Game and UI inputs and swapping between the two (like UE4)
• Full featured styler
• XML/JSON UI loading and/or editing

[Rover656]

This will be the last major addition before the Jam on Monday.

[Rover656]

This is ready for merge. We will now be able to use this in the jam starting Monday.