BuildingQOLs

Adds a couple of optionable QOL features.

1. 1 click belt/sorter building. Default behaviour is click #1 - mark for building start point, drag mouse, click #2 - build. Mod adds another one: hold - mark, drag mouse, release - build. So you can click - drag - click or hold - drag - release to build a belt/sorter.
2. Disable belt prolongation. Default belt building behaviour includes continuous belt building if you build it into nothing. End of the belt becomes a new start and you can left click for new end or right click to cancel. There is an option to disable that. Idea is to click-drag-release, click-drag-release, similar to factorio.
3. Show current altitude. There is an option to replace default tip near cursor (Choose starting position and Click to build) with "Altitude: n/ Length: m" or "A: n | L: m" (enable it in config) so you will always see your current belt altitude.
4. Auto take belt altitude. Starting a belt in another belt on any altitude changes your current altitude to that belt's altitude.