 Having got a route and schedule the user next selects the motive power.
 The user can drive ANY motive power over ANY route, although this may
 make a farce of the schedules which will indicate which power they are
 based around.

 For sake of simplicity, SIMUDRIVE carries a list of all the classes available.
 These are presented as a list which the user can move up and down, finally
 selecting the chosen motive power.

 Classes which are not in the user's library will appear in RED, while those
 that are in the library will appear in GREEN. If the user selects a class
 which is not in the library, then an error message will be displayed. In this
 case it is likely that the class has not been purchased.

 An option is supplied on the menu, to allow fast location of classes
 in a large list.

 Having selected the motive power, the user may now have to select a train,
 depending on whether the motive power is a locomotive, or a multiple unit.
