[Seaside] SeasideXUL improvements

[Pavel Krivanek]

Hi,

I did some useful changes in SeasideXUL
(http://www.squeaksource.com/SeasideXUL.html). Here is the list:

- support for latest Seaside 2.8
- Scriptaculous dependency removed
- ajax callbacks do not require response canvas so usage is now very
similar to standard Seaside processing. For example:

	xul button
  		onCommand: (xul ajax callback: [
			|  result |
			result := self call: XULComponent2 new.
  			self call: (XULComponent2 new text: result) ]).

	xul button
		label: 'answer';
		onCommand: (xul ajax callback: [self answer: 42	]).

- ajax-based support for an alternative to HTML forms with textboxes,
checkboxes, colorpickers, listboxes, menulists (inc. comboboxes) and
radiogroups. Their usage is very straightforward too:

	formId := WAExternalID new.
	xul form: formId with: [
		xul textBox on: #surname of: self.
		xul colorPicker type: 'button'; on: #color of: self.
		xul button
			label: 'Submit';
			onCommand: (xul formSubmiter
				formId: formId;
			callback: [ self refresh. ]) ].

Cheers,
-- Pavel