* handle FreeDB server errors gracefully
In my repeated tests, I ended up upsetting freedb.org, which started
issuing 502 errors. Those errors are not correctly caught by the
program which just crashes with a backtrace. Instead, we handle those
like any other API error, which can already be generated by
perform_lookup (but not handled).
The visible result for the user is that the CD is simply not found on
FreeDB, an acceptable compromise, in my opinion.
Closes: #206
* harmonize an error message with other warnings
... which are all capitalized.
021e621f84