Add a Cylinder tool

[Calinou]

• Related to Add a Staircase tool #16.

Add a cylinder tool that allows you to specify an angle arc where the cylinder should be drawn, then the depth by clicking a second time. The level of detail per full turn (probably 32 by default) could be adjusted in the toolbar.

It's important that the tool lets you draw cylinders that are not full-circle easily, as it's common to use 90-degree and 180-degree cylinders in level design (or sometimes even unusual values like 45-degree).

Since outward cylinders are convex, they can be created as a single block. Being able to create inward cylinders would be very useful in level design, but these must be drawn as separate blocks. This will likely require a lot of refactoring and may be better implemented separately (e.g. using a prefab system and a default set of prefabs).

[blackears]

Created first pass at this. You can create a basic cylinder now. Need more work to add extra features.