Improvements to whitespace and comments.
Make proper use of locals in f_dialog_init().
Use f_isset() (introduced by r250317) instead of `f_quietly f_getvar ...'.
Standardize NULL initialization to be consistent.
Make some obvious consolidations in local declaration for readability.
Add some additional debugging to the common media library.
Fix a copy/paste error within a comment.
Change the name of a couple of functions in `usermgmt/user_input.subr' to
make their purpose more clear by their names:

	f_dialog_input_change() and
	f_dialog_input_expire()

Are now (respectively):

	f_dialog_input_expire_password() and
	f_dialog_input_expire_account()

Upon revisit to this portion of code, the former names were too confusing.
Fix a bug in which the user's choice to Cancel was not properly recognized.
Fix a bug that would cause a spurious warning to appear to appear in an
edge-case. The case was that you have been through the FTP setup once before
and on the second time through, you cancel at the re-selection of a new FTP
server.

The spurious warning was "device_media: not found" and was caused because
the underlying call to f_device_network_down() did not check to see if the
network device existed before attempting to shut it down.

Add checks to make sure we don't forge ahead unless the device exists.
Fix a bug in which the user's choice to Cancel was not recognized. This was
caused by the standard (and correct) behavior of the shell to discard the
return status of lvalue-operands in a pipe-chain.

The solution is to not pipe the file-acquisition directly into sort(1) but
instead store the output (allowing immediate testing of the return status)
and later sort it.