improve vertex array handling in PositionAttitudeGeometry.
rename model::plan::Model to model::Plan.
store link_base::const_pointer in property::directory (instead of link_base::pointer).
cleanup interface of property::link.
simplify property::link_base::storage and property::directory::storage.
allow property::descriptor::storage() to return a nullptr when no parent is assigned (instead of throwing an exception).
make property::descriptor idependent of type wrapping facilities.
make property::link const in most contexts.
save storage instead of parent in property::descriptor.
make property::directory a base class (instead of a member) of config::Root, robot::Base and sensor::Base.
replace reference to parent with reference to storage in property nodes.
establish common node interface in property::node_base<…> (now a template).
make storage process of property::link more clear.
set property::node_base::storage and property::link_base::descriptor only in Storage::store(…) and Storage::create(…).
introduce convenience functions property::ref, property::cref and property::get for pointer_map_storage-managed links.