Removed text_edits parameter from process_single_source_file().

It was not used.
Remove the transform function that awaits only one filename.
Introduced option argument to the tranform() function.
Added a function to classifiy args and an incomplete test.
Extracted test__transform().
Framework for the degl executable.
Ignore degl.
The pointer to the const should also be const.
Started the implemention of the main program.