Converted to SCIFIO API

Updated the IO service and relevant commands to use SCIFIO-based
ImgOpener and ImgSaver instead of imglib2.
Translate cell img backed data as virtual stacks

The legacy layer now translates cell backed images to virtual stacks in IJ1.
However there is code to make sure that legacy changes to the first plane of
the virtual stack is syned back to IJ2.

There has been no change to minimizing isBinary() calls which will take
place after testing.
Display (V) in title of CellImg based data views
Display (V) in title of CellImg based data views
Title code now works when active dataset is null
Document pixel munging tweaks for virtual stacks
Document pixel munging tweaks for virtual stacks
Eliminate tracking of binary ImagePluses

We now always make 8-bit displays from 8-bit ImagePluses even if they are
binary (0/255) structures. This means that in order to get 1-bit the user
must explicitly run the type change plugin to 1-bit.

1-bit dataset data always maps to 8-bit binary ImagePluses and that mapping
is maintained via clamping (0,1) and promotion (0,255) by the pixel
harmonizers as needed.

These changes simplify the harmonization code and also can greatly improve
performance for degenerate cases with virtual data structures.
Added SourceOptimizedCompositeXYProjector

This is used for projecting CellImgs to planes, as Cell iteration is
very poor when done in flat order. This projector respects that
different channels may be in different cells, and follows the source's
natural iteration order.
Added PlanarCommand

Adds the PlanarCommand interface + abstract class, for commands that can
run on a single plane.
Add Dataset accessor method
Remove old plane caching approach
Updated scifio-devel dependency

Hard coded against 0.1.0-SNAPSHOT beta for now. May want to put this in
a central pom (e.g. scijava-common) and update.
Remove incorrect note
Change data type from Boolean to boolean
Finish changing types from Boolean to boolean
MergedRgbVirtualStack: add tests and fix bugs
Add some documentation
Minor code refactor
DefaultIOService passes context to ImgOpener

Instead of creating a new context each time ImgOpener is invoked, the
current context is reused.