Refactor non-DRY code to create ImagePlus instances

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Populate ImagePlus' FileInfo when converting from Datasets

This fixes a problem where the ImageJ 1.x macro command

	getDirectory("image");

would not report the correct directory, but instead an empty string.

Reported in http://fiji.sc/bugzilla/show_bug.cgi?id=761 by Graeme Ball.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Note in the FileInfo when the image was opened as a virtual stack

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
After loading hyperstacks, mark them as composite images

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'legacy-file-info'

This branch populates the ImagePlus' FileInfo after loading images
via SCIFIO.

This happens to fix the getDirectory("image") bug reported by Graeme
Ball in http://fiji.sc/bugzilla/show_bug.cgi?id=761.

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