Rework the deprecation message for ability/special descriptions.

Most notably, the name of the ability/special is now in the message,
addressing bug #20716. Firings are also limited to once per ability/
special per game execution.
Fix run-on sentence in the preferred format for deprecation messages.
Treat "yes" equal to "true" as attribute values.

(Also "no" and "false", of course.)
Fixes bug #20684.