Tweaked build paths a bit more...

To clarify, I discovered that the ProjectDir variable contains about the
following:

C:\projects\Nimbus\

This means that a path such as $(ProjectDir)\build\etc completes to:

C:\projects\Nimbus\\build\etc

Note the double backslashes. We discussed their relevance a few times
before, but I'm wondering if removing our own backslash will fix the
issues we've had. If not, we'll switch back to the previous solution.
Merge branch 'master' of https://github.com/dreac0nic/nimbusogreproto