small gpsim feature requests

Hi Scott et al,

Firstly, thanks again for fixing the 'over' command so that it now works
with 'call'.

Now, a couple of smaller requests:

 - in the source display window, any chance of you adding a handler
   for mouse wheel events in the main pane, so I can scroll using the
   wheel without having to position the mouse cursor over the right-hand
   scrollbar widget?

 - in the register display window:

     - among the bottom edge labels/fields for 'PC', 'status', 'W'
       and 'bsr', please consider adding additional labels/fields
       for the STATUS bits 'Z', 'N', 'C', 'OV' and 'DC'. (Yeah, I
       know, I should have memorised all the status bit positions
       by now, sorry)

     - please reinstate the left-edge labels showing the register
       addresses - the 0x00, 0x10, 0x20 etc

     - the blue highlighting of register cells upon a write to that
       register is great - but it would be really nice if this
       wasn't limited to cases where register has changed value.
       It's often helpful to know when a register with value 0x00
       has been overwritten with 0x00 (eg, when watching stack
       usage).

I'd have a go at these changes myself, but I don't know the GTK API, and
it would take me ages.

-- 
Cheers
David