Make method privat where appropriate
Started fixing JavaDoc
Fixed NullPointer in old Inverter
Fixed NPE in InvertNodeFactory (deprecated)
readded old InvertNodeFactory
Changed helper methods for column indices

	* Helper methods to retrieve column index now need DataTableSpec
	* More consistent with KNIME development
Refactoring NodeTools to NodeUtils
Added NodeUtils
unnecessary member variables removed
fixed versioning
fixed compilation error in org.knime.knip.tracking

	* due to renaming of NodeUtils
fixed settings model in TwoValuesToCellNodeModel
Improved Col Selection in TwoValueToCellNodeMod

	* same column shouldn't be selected twice
Improved Col Selection in GraphCutNodeFactory

	* Avoid the selection of the same column in column selections
bugfix 4748: merging images with different pixel type
Merge branch 'master' into clahe_revised