Don't force objects to have an id, especially since that id was
incorrect. "plap/plop" would have the same id as "plop", i.e. "plop".
We don't rely on the id for handling Collections anymore.
Change to use more unique property names.
Change the display, instead of using '*', we use '~', and there is no
"Collection" header anymore.
Updated formatters could use that way of showing the object is also a
collection too.
refs #774
fae4470101