usage of default suffix depending on filter in save as dialog (bug #43335) * file-editor-tab.cc (save_file_as): use QStringList for adding filters, initialize filter and default suffix depending on suffix of current file name if available, connect the selection of a filter to a new slot; (handle_save_as_filter_selected): new slot setting the default suffix depending on the first suffix in selected filter; * file-editor-tab.h: new slot handle_save_as_filter_selected