Unified application front-end

Introduces a single SPH application with support for

• named test cases without input files
• initialization from HDF5 files
• parallel HDF5 output with runtime selectable particle fields
• glass-like initial conditions (isotropic mean inter-particle distances)
• insitu visualization interfaces

Hilbert curve

• Adds support for using a Hilbert instead of Z-curve. Enabled by default, but switchable to Z-curve
• Fixed a GPU memory leak
• Partial support for HIP

Focused Octree

This release adds a new domain class that builds a locally focused octree based on
a slim coarse global octree and point-to-point communication.

Scaling test outputs:

SPH-EXA/v0.2.2

Merge pull request #82 from unibas-dmi-hpc/fix-cmake-cuda

fix CMake CUDA language detection

v0.2

Working Sedov and Evrard with MPI, OMP and CUDA.
The kernels uses a tree to perform all operations (neighbors, gravity, etc)