Extract result writing code into separate class
Rename GridCalc to IGridCalc

Preparation for adding GridCalc class.
Refactor common part of init() into new class
Coalesce two methods into one in parent
Add dependency on hdf-java
Remove hacky invocation of CCViz3D

Since this doesn't work well with the ResultWriter interface,
and is pretty ugly anyway, let's just remove it, and hope that
somebody will reimplement it properly later on.
Assume resultWriter is not null
Prepare for multiple result writers
Remove useless braces
Simplify ResultWriterText a bit before further changes
Stub implementation of HDF5 writer

This successfully creates the .h5 file with one array.
Move common voxel code into VolumeElement

No functional change.