Add support for dynamic creation of vectors, sets, and maps

[bloer]

• vector. Syntax: [ item1 , item2 , item3 ] .
• set. Same syntax as vector
• map. Syntax: [ key : value , key : value , key : value ]
• append syntax: prefix opening with '+' for any style
• Make sure that vector and map interfaces are JSON compatible

Questions?

• Should we also allow enclosing () rather than [] ? Or should we enforce that () encloses fully pre-defined entities like ParameterLists, while [] enclose dynamic entities?
• Should we require separating commas between elements?
• Should we require the separating colon between key value pairs in maps?
• Should we keep ParameterLists as they are, or switch them to use the underlying map functions?