factor out ViewerImgLoader as an interface (implemented by Hdf5ImageLoader)
such that there can be other backends besides hdf5 eventually.
safety check
Merge branch 'importer'
Added better method to extract approximate rotation from affine transform.
The plane that should be respected by the approximate rotation can be chosen.
refactored IO timing out of Hdf5GlobalCellCache.
(there might be other caches at some point)
removed local jhdf5 repository because it now lives in maven.imagej.net
http://maven.imagej.net/content/repositories/releases/cisd/jhdf5/
added copy() methods for ViewerState and SourceState, and methods to get state from SpimViewer.
set initial transform to show center slice of first timepoint and set brightness
using a histogram of that slice.
remove left-over debug printlns.
Add a helper to perform renaming merges

A "renaming merge" is a merge of an originally independent project into a
subdirectory. In this particular case, it is the merge of the SPIM Viewer
into fiji.git's src-plugins/spim_viewer/ directory.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Renaming merge of 'tobias-spimviewer/master' into src-plugins/spim_viewer

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>