Save SIMPA version number in output

[TomTomRixRix]

For reproducibility purposes it would be nice to have the SIMPA version saved in hdf5 files. The users may in the future go back to old releases and read in the data.

In the long run, perhaps even saving the git commit hash value would be interesting, but for now the version number should be fine.

[jgroehl]

100% agree!

[kdreher]

The solution with pgk_resources keeps causing problems so we will need to find a different one