Custom action parameters on widgets, folder widget enhancements

[amro]

I needed to extend the folder widget for a prototype a client of ours
is building. This required custom actions on widgets to support
parameters (similar to on="l:foo then selectOption[bleh]"). I've
added said support to head and also added some of the necessary
functionality to the folder widget. I think there's still some stuff
left to do but the following actions are now available on the folder
widget: open, close, openAll, closeAll, selectItem.

Here's a sample on expression (on an opening folder tag):

<app:folder id="folder" on="l:openall then openAll or l:closeall then
closeAll or l:select then selectItem[folder=0,item=2] or l:open then
open[folder=0] or l:close then close[folder=0]">