Patches, Const Scalars, Py Containers

Scalar records properly support const-ness. The Particle Patch load interface was changed, loading now all patches at once, and Python bindings are available. Numpy dtype is now a first-class citizen for Python Datatype control, being accepted and returned instead of enums. Python lifetime in garbage collection for containers such as meshes, particles and iterations is now properly implemented.

Thanks to Axel Huebl and Fabian Koller for contributing to this release!