Close #419 Radiation Adds HDF5 Output/Restart

This pull request:
- adds hdf5 via libspash to radiation plugin
- removes amplitude data as pure binary 
- instead adds amplitude data as HDF5
- adds correct checkpoints via HDF5
- adds automated restart
- improves seperation between communication and data write

It solves #419.

In upcomming pull requests:
- conversion factors to SI
- observer directions
- frequencies

will be stored in the HDF5 files as well
and tools for data analysis will be created. 
To calm down the Gollum inside of you:
If the future HDF5 anaylsis tools for radiation reaches the level of sophistication of the current ASCII tool and after not only the data but also attributes are included in the HDF5 output, the need for the ASCII output **does not need to be replaced** by HDF5 output, but instead **can be removed** in its current form, since the HDF5 amplitude output allready contains both `totalRad`and `lastRad`. 
(The usefulness/need for an optional ASCII output can be discussed by all developes seperatly at a later stage.)