Add Counter struct.

This can be used for counting of meshes or other object instantiations etc.
Use BaseLib::Counter<Mesh> for mesh id.
Add UniqueMeshId test.
Merge pull request #98 from endJunction/AddMeshId

Add mesh ID.
Adding std::array ctors to TemplateXXX.

Using std::array is safe, so users should prefer this constructor to the older constructor with pointers.
Updated submodule ThirdParty/VtkFbxExporter
Install xsd files.
Added missing include for OpenSG.
Revert "Added missing include for OpenSG."

This reverts commit 5e9c0be7adcc015f0855c1313e6998439f2b8efd.
Updated submodule ThirdParty/VtkFbxConverter.
Fixed linker error.
Fixed a warning.
Updated submodule ThirdParty/VtkFbxConverter.
Updated submodule ThirdParty/VtkFbxConverter.
Merge pull request #99 from endJunction/TemplateXXX_Ctors

Adding std::array constructors to TemplateXXX.
Updated submodule ThirdParty/VtkFbxConverter.
Updated submodule ThirdParty/VtkFbxConverter.
Fixed a bug in algorithm for determining neighbour cells.
Merge pull request #106 from TomFischer/BugFixGrid

Fixed a bug in algorithm for determining neighbour cells.