We now create the correct user defined default material.
Fixed error message to match XNA.
Throw an error when vertex weights are not found for skinned models.
Added exception when the skeleton is not found for a skinned mesh to match XNA.
Added exception to match XNA for wrong weight format.
Fixed storage container creating existing directory

Made storage container code check if the directory exists before
creating a new one over the top.

The previous behaviour was causing a crash on software created using the
PSM build (and perhaps others) of MonoGame.

Refer to issue #3061 for more information.
Added a test for ModelProcessor.DefaultEffect, but the assert is disabled for now.
Fixed test for vertex weights.
Merge pull request #3068 from SickheadGames/defaultmat

Fixed ModelProcessor.DefaultEffect
Fix ReleaseAllTouchesTest
Merge pull request #3069 from danzel/releasealltouchestest

Fix ReleaseAllTouchesTest
Moved directory exists change to the right function

Directory exists check now in CreateDirectoryAbsolute as per issue #3061
for pull request #3067.
Merge pull request #3067 from lordoaty/develop

Fixed storage container creating existing directory