only reveal following count on tiddlers visible in displayArea
only reveal following count on tiddlers visible in displayArea

added config.extensions.tiddlyspace.scroller
This allows you to assign functions that will be called when a tiddler
becomes visible in the display area.

The follow macro now assigns an event to the tiddler it belongs to via
registerIsVisibleEvent
The scroller takes care of the rest.

FND/tiddlyspace,FND/tiddlyspace,TiddlySpace/tiddlyspace,TiddlySpace/tiddlyspace,FND/tiddlyspace,TiddlySpace/tiddlyspace