SHORT TERM
----------

* Volume output: allow more options to be passed to the output method,
so that the user of the library can potentially output the volume in a
different data-type than what they loaded it in.

* Documentation: allow for the automatic generation of the doxygen
documentation. 


LONG TERM
---------

* Templates: create a template class which works directly with minc
(as opposed to volume_io) and uses the netcdf data-type as the
template type. Should allow for better memory usage and speed
optimisations, but will lose the benefits of the volume_io caching.