Added sphinx documentation for gui (attention contains binary images!)

modules/gui/doc/gui.rst

modules/gui/doc/images/100208_OpenStructure_UI_Colored.png

modules/gui/doc/images/100208_Scene_Win.png

modules/gui/doc/images/100208_Tools.png

modules/gui/doc/images/100210_auto_completion.png

modules/gui/doc/images/100210_multi_line.png

modules/gui/doc/images/100210_path_completion.png

modules/gui/doc/images/100210_single_line.png

modules/gui/doc/images/100614_Inspector_gadget.png

modules/gui/doc/images/100614_context_menu_view.png

modules/gui/doc/images/100614_entity_context_menu.png

modules/gui/doc/images/100615_conservation_1.png

modules/gui/doc/images/100615_conservation_2.png

modules/gui/doc/images/100615_property_type.png

modules/gui/doc/images/100615_secondary_structure.png

modules/gui/doc/images/100615_select_display_style.png

modules/gui/doc/images/100616_copy_paste.png

modules/gui/doc/images/100616_zoom_in.png

modules/gui/doc/images/100616_zoom_out.png

modules/gui/doc/images/100617_search_bar.png