Remove unnecessary files.
Adding .vtk as a supported format for mesh sequence timesteps

Also, removing some commented code.
Properly handle sequences with varying topologies.

I just handle every case with a shallow copy, it probably even has a
better performance.
Refactor workspace and workspace factory

Added MED_WORKSPACE_INTERFACE macro in medAbstractWorkspace, which
automagically creates a series of static and instance methods to
standardize and simplify the regsitration of a workspace. Also, sorts
workspace by name in the menus.
More unused files removed.
Refactor data and data factory

Added MED_DATA_INTERFACE macro in medAbstractData, which
automagically creates a series of static and instance methods to
standardize and simplify the regsitration of a data type.
Refactor toolbox and toolbox factory

Added MED_TOOLBOX_INTERFACE macro in medtoolbox, which
automagically creates a series of static and instance methods to
standardize and simplify the registration of a toolbox.
Refactor settings widget and setting widget factory

Added MED_SETTINGS_INTERFACE macro in medtoolbox, which
automagically creates a series of static and instance methods to
standardize and simplify the registration of a setting widget.
Remove double save window at application quit
Add pan icon for those who don't have a middle button
Click twice on quick acces menu hides it again
Add view close in registration workspace
Add single remove/save option to bundle list
Pan icon is now svg
Remove data categories
Disable offscreen rendering before destroying rendering window, to avoid crash
A few corrections to tensor interactor
Visibility change was not rendered for fibers
Fix crash when removing a tab in diffusion workspace.
Merge pull request #151 from fvichot/remove-data-categories

Remove data categories