Terrain objects are not shown in minimap

[elliotrpage]

The minimap does not show terrain items, making it difficult to know at a glance the "lay of the land".

Terrain will differ from Units in that once revealed they should remain displayed on the minimap even when shrouded by the Fog of War. Alternately, they could be shown in the minimap by default and not need to be revealed (You assume that players already know the battlefield they are fighting on)

Here is an example from Age of Empires 2 to illustrate what I mean:

Edit: I am tempted to have a stab at this myself, but wanted to submit an issue first as mentioned in the README!