Command line arguments. Generate file lists.

Implement basic command line arguments to specify which files to operate
on. Also generate a list of the identified files.

Only *.c files are accepted (for now).

Ex:
	convert.py [-r] [-d] [files...]
	r -- operate recursivly into all sub directories
	d -- operate on all files in the current directory
	files -- list files to operate on (optional w/ [r/d])