Add wizard to fp lib dialog to easily add entries to this table.
fix compil issue on Linux
Add a wizard to the footprint library table dialog editor, to help users to select the right plugin, an existing enviroment vairable or an absolute path, and addl a list of new entries to the table.
Note: the wxWidgets webkit/webview library is needed.
On windows,there is no problem.
On Linux,  the libwebkitgtk-dev tool (sudo apt-get install libwebkitgtk-dev)  must be installed if it is missing (and wxWidgets rebuilt).
However, to avoid use of wxwebview, you can compile kicad with cmake option -DKICAD_USE_WEBKIT=OFF.
But the github plugin wizard will be not available.