Change Parameter notation's scope to only affect the next element and introduce notion of group

• Thomas and I would like to split the current begin/endDocument() events by adding begin/endGroup(). We're currently reusing the same event for group usage (with the (((...))) syntax).
• This will allow us to write things such as (%...%)(((....))) in order to add parameters for a group of standalone blocks
• We also propose to remove the (%...%)...(%%) notation in favor of (%..%)(((...))) notation
• (%..%) will always be applied only to the next element, even for inline content.

See http://markmail.org/thread/kqlaoshxgkafsldu for details