function celt (name, clazz) {
			var e = document.createElement(name);
			e.className = clazz;
			return e;
		}
Builds and returns a visual diff view.  The single parameter, `params', should contain
the following values:

- baseTextLines: the array of strings that was used as the base text input to SequenceMatcher
- newTextLines: the array of strings that was used as the new text input to SequenceMatcher
- opcodes: the array of arrays returned by SequenceMatcher.get_opcodes()
- baseTextName: the title to be displayed above the base text listing in the diff view; defaults
	   to "Base Text"
- newTextName: the title to be displayed above the new text listing in the diff view; defaults
	   to "New Text"
- contextSize: the number of lines of context to show around differences; by default, all lines
	   are shown
- viewType: if 0, a side-by-side diff view is generated (default); if 1, an inline diff view is
	   generated