Added a very basic feedback affordance for Saved
Fixed a subtle bug in object creation

Because of mishandling of the idea of the "root", indirectly inherited
properties were being misattributed in the creation screen.
Added InstanceEditPropsProp

You can now specify, in a Model, which Properties should be shown to
edit in its Instances.  This is a cheap and dirty step towards true
custom edit screens, and should make it less painful to build the
invitee list.
Added the "Done and Create Another" button

This should make bulk input a bit less awful.
Improved the warning if _me isn't found

Did this by introducing the notion of WarningValue and TypedValue.cut,
which tells the processor to stop here and not keep processing the error
message.
We now cope properly with nested Style blocks

Granted, we do this by being excessively forgiving -- we no longer check
that the start and end line up.  But getting this wrong just produces
mismatched HTML, and that typically isn't tragic.