Automatic Underground Pipe Connectors for 2.1

OG mod here: https://mods.factorio.com/mod/automatic-underground-pipe-connectors

(this release will be deleted as soon as Sparr finds the time to release himself - daz96050 and pacak did the initial effort to port it to 2.1)

--- original mod description following

Automatically places a pipe when two undergrounds are placed at a corner or one space apart. Places a ghost pipe if you place a ghost underground. Also places connecting pipes or ghosts if you're placing appropriately near an assembler, chemical plant, pump, etc.

Reads recipes to identify and support modded pipes. Confirmed working with Bob's Logistics and PyHighTech, should work with most other mods that add new pipes as long as they follow the pattern of the underground recipe having the matching pipe item as an ingredient.

Not compatible with SchallPipeScaling both because the pipes are big and because the recipes are indirect.