Spinner is more modal now, and can be forced to stop fully.
Listen for component failure during init and abort fatally.

A component failure during init is more problematic, because there is never
a valid place. A lot of code assumes that reader.getPlace() will return a
valid place object -- which must have a component object, but none was ever
fully instantiated.
Fatal messages - browser incompatible, initial components failed (fixes #169).