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: optional field converter.

* You can now optionally specify a converter that does the actual
message to settings conversion, and vice versa.
* This allows for more sophisticated and custom conversions.

libshared: Factored out driver settings class from net_server.

* The new class is called DriverSettingsMessageAdapter which can translate
between a driver_settings file, and a BMessage.
* The net_server Settings class is now just using this class.

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: optional field converter.

* You can now optionally specify a converter that does the actual
message to settings conversion, and vice versa.
* This allows for more sophisticated and custom conversions.

libshared: Factored out driver settings class from net_server.

* The new class is called DriverSettingsMessageAdapter which can translate
between a driver_settings file, and a BMessage.
* The net_server Settings class is now just using this class.