3D GUI updates

[smlpt]

This PR adds VR GUI functionality from microscenery and jans branch, and tweaks it to work without further dependencies.
This includes UI elements like Button, Tabbedmenu, Switch and Textbox, as well as layout elements like Column and Row.

It also updates VRTouch, VRGrab and VRPRess interactions from @moreApi's branch.
Further updates: VRTouch objects can now be interacted with custom nodes (think tool tips) instead of just the controller hitbox. Buttons can now optionally be triggered by touch only, not necessarily requiring VRPress behavior anymore, and custom colors and pressedColors can be passed to them.

[smlpt]

This PR now also includes a flag/attribute for Node.generateBoundingBox and the BoundingGrid class called includeChildren. It is set to true per default to not interfere with the previously implemented behavior. If set to false, it will only return the bounding box of the node itself, without considering its children.

[moreApi]

I unsibscribed from this PR because I got an notification for each little commit. Just add or poke me again, when my attention is required again.