Small Map Modifications

I've done the following to the map. This is mostly to try and see if I can use that fucking map tool and also to follow a few requests I've seen here and there :

- Create a tunnel going from Bar Maintenance to the Holodeck, complete with 2 crates and an Holodeck Maintenance Door
- Creating an half-finished wall south of Engine. It's made out of 5 rwalls disposed in a 1-3-1 pattern, a light, another danger sign, and is supposed to be completed with grilles
- Added a lightbulb and a lightswitch to the Art Storage
- Added a catwalk from Disposals to the MoMMI nest entrance, and changed both double-airlocks accesses with an external airlock on Disposals, and an AI-core level access glass airlock on the MoMMI Nest

I've never used Git Hub for files before, so I don't know how to include a file, here's the link : https://github.com/dylanstrategie/vgstationmodif/blob/master/tgstation_map_mod