Improve LibreCAD Wiki

hi
I Found some mistakes in this linkhttp://wiki.librecad.org/index.php/LibreCAD_v1_Developers%27_Handbook

here,
there is no information about src/fileio/  

and
in src/ui/
rs_actionfactory  is written instead of qg_actionfactory
rs_actionhandler  is written instead of qg_actionhandler

Please feel free to edit it.