* Icy let you select appropriate importer when multiple choice are
available.
* Loader: many changes to provide better support on
FileImporter and SequenceFileImporter classes.
* FileImporter.acceptFile(..) method now use path parameter.
* Layers panel:
 - opacity setting has moved at bottom.
 - support custom setting panel per layer (Overlay.getOptionsPanel())
* SequenceUtil:
 - C/Z/T merge operation now preserve metadata.
 - added getSubSequence(Sequence, ROI, double) method.
* User email information stored in preferences.
* some refactoring:
 - ImageLoaderDialog --> LoaderDialog
 - ImageSaverDialog --> SaverDialog
 - LoadDialog --> OpenDialog
* others minors improvements, bug fixes and cleanup.
* minors changes on VTK library on Unix system.
* fixed crash on exit on Unix system (temporary workaround for JVM bug)
* Sequence:
 - added hasOverlay(Class clazz) method
 - added getROI/2D/3Ds(boolean sorted) methods
* SearchBar: faster result display / refresh of search bar/
* Better internet connection monitor (lighter on network traffic).
* faster background repaint (cached), more responsive when moving
windows.
* fixed XLSUtil.loadWorkbook(..) which was clearing file.
* minor changes on VTK canvas shutdown.
* minor tweaks / improvements.
* refactoring.
Merge branch 'develop' of https://Stephane-D@github.com/Icy-imaging/Icy-Kernel.git into develop
* Fixed ROI2DEllipse area calculation
* Rewrote ROI2D and ROI3D perimeter calculation with a more precise approximation
fixed formatting in previous commit
Merge pull request #603 from adufour/develop

Fixes to ROI area and perimeter calculations
* fixed ROIUtil.getMassCenter() method.
* modified ROI2DPoint rendering.
* fixed vertical and horizontal ROI2DLine selection.
* added ROI contour size field (only for drawing).
* loader dialog show image preview even for "all files" filter.
* added GeneralPreferences.get/setLoaderFolder(..) to retrieve the
current "Open" folder.
* do not clear (remove ROI and overlay) sequence object on close (GC
should do it anyway)
* changed way of closing opened windows on exit.
* fixed histogram refresh.
* fixed InstanceProcessors.submit(..) method.
* tweaks / fixes on GUI refresh.
* refactoring.
* fixed shared LUT on viewer duplication (regression).
* Postponed VTK object creation in ROI2DShape.
fixed minor bug on viewer close.
fixed minor regression.