wmxmled.py: simple xml editor by wxPython

TODO
* test on other platforms (now tested only on Linux-GTK env.)
* add wm3d specific functions

CHANGELOG
2014/04/14: add about & translations & code rearrangement.
2014/04/10: arrange code and add comments, and minor bugfixes.
2014/04/09: implement and improve multiple copy, cut, delete functions
2014/04/07: fix and improve undo functions (paste, del, add)
2014/03/14: read file from command line argument
            fix bug on removing attributes
            add multiple delete (ad hoc); multiple copy/cut is not supported yet
2014/02/17: implement find and multiple edit (experimental)
            some minor bug fixes
2014/02/10: add parse error handler
2014/02/09: add EVT_DROP_FILES handlers for controls (not checked)
2014/02/08: fix crash when undoing delete (just avoid segmentation fault).
            some actions cannot be undoed, though.
2014/02/02: implement simple undo & redo functions (still buggy)
xxxx/xx/xx: prepare git repository
