sfeed_opml_export: sync loadconfig() function fixes from sfeed_update

- Do not show stderr of readlink.
- Show the reference to the example sfeedrc (like sfeed_update).
- Make the error message a bit shorter.
- Fix showing the path if it does not exist, for example:

	$ sfeed_opml_export "a"
	readlink: a: No such file or directory
	Configuration file "" does not exist or is not readable.

Now shows:

	$ sfeed_opml_export "a"
	Configuration file "a" cannot be read.
	See sfeedrc.example for an example.

0 files changed, 0 insertions, 0 deletions