When overriding greenhouse the plants and player objects don't persist

[weeryan17]

This might be related to issue #20 but as no description was provided for that issue I only have a vague idea what that issue is about. The main issue is when you make a content pack and you specify an override for the green house map say

"Overrides":[
		{
			"MapName":"Greenhouse",
			"FileName":"Big-floor-1-Greenhouse"
		}
	]

The plants and any objects placed by the player don't persist.

Also you can't specify the greenhouse entrance when overriding greenhouses witch causes them to warp in at the wrong location with bigger maps with no real way to override it