DriverSettingsMessageAdapter: added "wildcard" support.

* You can now add arbitrarily named fields to the message as well,
without having them all specified in the template.
* Also added a missing converter method that is called when there
are no values to add, and implemented all methods in the base
class, so that you only have to implement the methods you actually
need.

DriverSettingsMessageAdapter: fixed converter signature.

* The ConvertFromDriverSettings() method missed the current value
index.
* Completed unit tests, and enabled them all.

DriverSettingsMessageAdapter: fixed various issues.

* _AddParameter() would ignore all BMessage::Add*() errors.
* _ConvertFromDriverParameter() would ignore most intermediate error,
but would fail badly over some incorrect settings file.
* Also, it checked for the parent value for each parameter, which
doesn't make any sense, but would add as often as there are
parameters -- which also may be none, in which case the value
got ignored.

DriverSettingsMessageAdapter: added "wildcard" support.

* You can now add arbitrarily named fields to the message as well,
without having them all specified in the template.
* Also added a missing converter method that is called when there
are no values to add, and implemented all methods in the base
class, so that you only have to implement the methods you actually
need.

DriverSettingsMessageAdapter: fixed converter signature.

* The ConvertFromDriverSettings() method missed the current value
index.
* Completed unit tests, and enabled them all.

DriverSettingsMessageAdapter: fixed various issues.

* _AddParameter() would ignore all BMessage::Add*() errors.
* _ConvertFromDriverParameter() would ignore most intermediate error,
but would fail badly over some incorrect settings file.
* Also, it checked for the parent value for each parameter, which
doesn't make any sense, but would add as often as there are
parameters -- which also may be none, in which case the value
got ignored.