finished argument parsing.

f() now accepts a list of files as arguments. These files are checked by
type and added to their appropriate type lists. The type lists are then
executed upon. For example, one can pass these arguments to f():
( "file1.tar" "text_file1" "text_file2" "image.png" )
to extract file1.tar, edit text_files{1,2}, and view image.png.
sudoedit works too. If a single text file is not writable. The user is
prompted to use sudoedit.