Added a rudimentary image attribute

This is a straight forward implementation of the image attribute. It's not memory efficient.
Removed some import statements that are currently not used

They where left during playing around with the image integration.
First version of the image support

Using DataContainer (buffered) to store the image data in the plate model (slows down parsing, but keeps the view slim).
The WellViewer got two constructors for the tooltip and the view. using TableView to display the image data.
Adding small information window to the HeatWell to informa about the launching of the WellViewer.
Changing the image data parsing in the HeatMapViewerNodeModel.
WellViewer small adjustments
added a method to the AttributeUtils.

its for finding the column in a input DataTable that holds the color handler and returning the Attribute of that column.
adding .gitignore files
Incrementing the version numbers

hcstools and knutils are now 1.3
Changed the scriptingcore and the "scripting r" to be consistent with the version numbers found on the update servers (eclipse p2 at cbg and knime-community)