Load Tiled Map XDocument
At the moment, you only can load a tiled map with a file that is saved as a file on the disk.
It should be possible, to load a tiled map from a XDocument object or provide your own WaveDocumentLoader.
With that, you could load maps, that you create on the fly.
There also needs to be support for polygon, polyine and circle objects to be created as entities. Currently only rectangles can be.