propose function name as file name when saving a new file (bug #42568) * file-editor-tab.cc (get_function_name): new function, get a possible function name from the contents of the file; (save_file_as): when saving a new file, try to detect the function name by get_function_name and propose this name as file name * file-editor-tab.h (get_function_name): new function

Copyright notices are intentionally omitted from the files in the
examples directory.  We don't want copyright notices cluttering the
manual.