added options.editorOptions and column definition field 'editorOptions' to allow us to pass custom options/settings to the various column editors, e.g. the DateEditor. Example column[] definition array shows how to spec a different calendar image than the default assigned by slickgrid itself:

	var columns = [
	  {id: "registration_date", name: "Registration", field: "registration_date", minWidth: 60, editor: Slick.Editors.Date, sortable: true, editorOptions: { dateButtonImage: website_rootdir + "/images/CALENDAR.PNG" }},
	  ...
	];
slickgrid DataView: added globalItemMetadataProvider option and group definition option getGroupRows (function/callback) to allow a more flexible construction of the row list, based on the grouping. Using the custom getGroupRows() callback implies that you can now create 'grouped' views which are not strictly hierarchical any more.
partial whitespace police raid