Render and UI back-end redesign and Chunk view and tool

Additions:

• A top down 2D view for easier navigation and viewing.
• A chunk tool for modification of chunks.
• A prune operation has been added to the chunk tool.

Changes

• The delete chunk operation has been moved into the chunk tool
• The canvas (the object everything is rendered onto) has been reworked quite a lot to simplify it. Most user facing things are where they were but other things have moved into nested classes in the canvas. You may need to fix your imports if you were importing EditCanvas
• Previously the canvas did far more than it should have been doing which meant that each tool was rather powerless. This has now been flipped to give each tool full control. Each tool now handles its own user interaction logic, rendering and other logic. The canvas still retains some attributes to allow the tools to communicate things like the state of the box.
• The selection box has been redesigned. Each tool now controls the behaviour and rendering of the selection. The chunk tool has a new custom selection logic to allow selecting whole chunks. The original select tool has been improved to make it easier to select a single face on smaller boxes. This is still a work in progress.
• The selection class has been redesigned to make it immutable and a lot more logic added to it eg. to allow merging selections.

Lots of other bug fixes and changes that I have forgotten about.