[Gnumed-devel] update mechanism for gmGP_ use cases.

[syan tan]

   when the gmPatientSelector creates a new current patient object, the 
ui's need to know the model has changed.
I used gmDispatcher to send a patient_object_changed() signal , and got 
the gmGP_  widgets to inherit from a patient
holder class that listens for that signal; the signal is parameterized 
with the new current patient object, so each
gmGP_ object can know when the model has changed, and can save unsaved 
data in the old patient model,  and with the new patient model, update 
lists displays, and clear edit areas as needed. 

I thought that was a pretty direct way of using the current framework, 
and isn't clever or fancy or stepping on anyone's shoes.

see test-area/test-client-c  for changes to wxpython/patient/gmGP_*  .