* Add polygon library.

*all* the nested files and directories within the current working directory, it scans the first 
level of files and directories.  When a user double-clicks on a folder, *then*
the childeren of that directory are added to the wxTreeCtrl.  This means that the little 
triangle does not appear until the user opens a directory .. but, i think this is 
a worthwile price to pay given below. 

This prevents (or at least mitigates) memory overflow in the case that kicad starts in root, or, 
in my case, it starts in my home directory, where thanks to wine & other sw,  
there are far too many directories. 

also modified the TreePrjItemData so that it stores the full pathnames in m_FileName, 
not paths relative to the CWD.  I'm not sure if this is the correct thing to do, 
especially with the python interface, so change it back if it is more complicated. 

the move and rename commands threw a segfault on my system 
(Debian etch, wxWidgets 2.8.7), 
and since there are better ways to rename and move files, this functionality 
was disabled until somebody can fix it (alas, I don't have time for this now)