'G'rab grabs furniture if vehicle is not present, for a friendlier oh-shit-monsters-block-the-door UI experience.

After 'G'rab grabs a qualified furniture, it can be moved until pushed out of the way or let go of. Similar to cart grabbing, moving towards the furniture pushes it and the player forward a tile, and away pulls it and the player backwards a tile. Unlike cart grabbing, this is:
* Much more noisy and expensive, timewise
* Unless pushing or pulling, directional keys move the -furniture- while the player stays still, just like in the construction menu.
* Grab releases if the furniture is moved a tile away from the player (ie, furniture is North East and player pushes North);