Fix utf8 file names issue in linux

For whatever reason wxGTK does some switcheroo of the encoding
used for filename strings (used by wxFopen and alike) when
wxApp is initialised and not before. So you are forced to
create wx.App() before attempting to load pcb even if you don't
need any windows.
:bleh:

Author: qu1ck

InteractiveHtmlBom/generate_interactive_bom.py

@@ -647,14 +647,14 @@ def Run(self):
     config = Config()
     config.add_options(parser)
     args = parser.parse_args()
-    if not os.path.isfile(args.file):
+    if not os.path.isfile(args.file.decode('utf8')):
         print("File %s does not exist." % args.file)
         exit(1)
     print("Loading %s" % args.file)
-    board = pcbnew.LoadBoard(os.path.abspath(args.file))
+    app = wx.App()
+    board = pcbnew.LoadBoard(os.path.abspath(args.file).decode('utf8'))
     if args.show_dialog:
         # Create simple app to show config dialog, infer config.
-        app = wx.App()
         dlg = dialog.SettingsDialog(None, extra_data_func=parse_schematic_data)
         config.netlist_initial_directory = os.path.dirname(args.file)
         config.transfer_to_dialog(dlg.panel)