Recent unit test structure work and Eclipse prep

Making a PR for this to both see all the changes in a nice format and for some quick review / sanity checking. I'll likely append a few more commits before merging, hoping to fix all the pathing quirks surrounding the use of natives then take out the associated debug logging first.

@msteiger - you might want to take this for a spin in Eclipse? It looks promising though, @mkienenb checked it and it looks to be an improvement. It includes #755 and thoroughly fixes https://github.com/Nanoware/Terasology/issues/54 among other things