XRCed: invalid growables for grid sizers

hello!

XRCed stores growablecols and growablerows parameters for wxFlexGridSizer and wxGridBagSizer as a list of nodes, like this:

     <object class="wxGridBagSizer">
       <growablecols>0</growablecols>
       <growablecols>2</growablecols>
     </object>

but xrc loader requires these parameters to be a comma-separated list of numbers, like this:

     <object class="wxGridBagSizer">
       <growablecols>0, 2</growablecols>
     </object>

to work around this, i have added 'growablecols' and 'growablerows' to the 'allParams' lists for classes xxxFlexGridSizer and xxxGridBagSizer in XRCed/xxx.py, and disabled 'specials' and 'paramDict' definitions in these classes. there definitely is a better solution...

best wishes,
alex.