Remove 'parcel' explicit exposure specifier.

Remove 'parcel' as an explicit exposure specifier, but leave unspecified
exposure as implicitly indicating parcel-scoped exposure.
Remove bogus token 'local'.

The exposure specifier "local" can only be derived from context -- it
can't be specified using a keyword.
Enable accidentally disabled tests.
Remove `private` from CFCParser.

Remove the `private` exposure specifier from the parser.  The private
ACL is still supported by the underlying model classes, though.
Restrict visibility of member vars.

Disallow exposure specifiers for member vars.  Change the default
exposure from ostensibly `parcel` to `private`.