Automatically build items under your cursor, if the correct item type is in your cursor.

This is based on AutoGhostBuilder, but only works for items in your cursor. Pro-tip: select items with pipette! The goal here is not to build faster or replace bots, but to relieve the tedium of clicking, especially with accuracy, when placing blueprints early game.

This behaviour will also correctly handle belt direction, tiles, and entity upgrade/downgrade. Undo is properly supported as well.