Permit content to be supplied directly to shortText

This lets one use ie. text_lead() instead of the HTML lead.
Use Admin::Articles' retrieveArticles instead of handleListRequest
Fixed title and lead escaping
Handle hideblock and subtract

hideblock specifies a block which is to be hidden to calculate size,
this may differ from the blocks whose content we are height limiting.

subtract adds some additional pixesl to be subtracted, this lets you
compensate for miscalculation as a result of using hideblock.
Added a separate scrollbar for folders
Don't warn about missing formbuilder