support for individual per-source mipmap definitions
(although the hdf5 does not yet provide it)
started multi-threaded rendering. timing needs to be resolved.
added timeout to Hdf5GlobalCellCache, after which empty cells are returned instead of loading from hdf to cache.
double-buffered rendering
first attempt at SpimRegistration import dialog.
hack avoid rounding errors when computing best-suited mipmap level.
remove unused code
create sequence-description xml with base path relative to location of the file.
change visibility of some methods for use by CATMAID tile server
report hdf5 creation progress to a ProgressListener interface