Improve the GUI

[hildogjr]

Improve the GUI:

• Synchronize the Py GUI code to the kicost_gui_wxFormBuilder.fbp GUI project file;
• Add a listbox to use as BOM files to open instead the combobox. Add "+", "delete" and "up" / "down" buttons as the KiCad icons;
• Add a secondary listbox or a use the above with a checklistbox (default ON to use as BOM) to, when OFF if the same that above, to use in Allow use a BOM just for manf# #360. Need fix Remove the necessity of specify EDA (class code model) #359 first;
• Remove the "Recognized EDAs" list, depend of first fix Remove the necessity of specify EDA (class code model) #359;
• Fix the "About" tab: the images sizes and the "Credits" have to go to a different about dialog;
• Fix the progress bar;
• Fix the "Convert to ODS" capability in the GUI;
• Enhancement at the "Configurations" tab: missing checkbox option (show_cat_url and others...), add some graphical element to make clear the KiCost CLI and GUI configurations group, and more;
• Shows the last fix and new (use the HISTORY file) on the GUI startup. Look for entry==GUI_NEWS_MESSAGE_ENTRY: in the kicost_gui.py to the implementation point;
• Fix the 'AUTHOR.rst' read on GUI (currently it is not reading the file);
• Open the file and list the variants into the GUI to allow the used make a graphical choose;
• Change "Convert to ODS" to "Save as .ods", use some improved extension check to also achieve this option Text improvement #411.