A lot of small fixes (desc.)

External resources now always use the constructor-calling assembly for
loading their crap.
Drawing of filled rectangles.
Removed the Type in DrawJobs as a simple GetType should suffice.
View can now be set to always have the same size as the output size
(AreaSizeIsViewportSize).
Replaced Window.GetSize with a property, since it's now fast to check.

This is all stuff I'm running into while working on a possible
level/resource editor.