Added checks for JpGraph library

Note: JpGraph seems to no longer be supported, maybe we should look for
a replacement in a future release.
Fix bug with verbosity links

Regression introduced by 527d9faf95884c7d260eeaaf27aa926c0ea5c194,
prevented user from swiching the 2 flags individually.
Reflow long lines
Proper processing of unhandled errors

Sometimes the execution of a test itself can trigger an error, and in
some cases the test can be successful despite of that (e.g. a PHP notice
or use of deprecated functionality). The code was not handling these
situations properly when $g_show_all = true, causing the test to
continue silently instead of reporting the problem.

Added a case for E_DEPRECATED and clarified description for unhandled
error types in check_print_error_rows(). Also made sure the error is
properly captured  when hiding passed tests and/or verbose error
messages are not shown.

Fixes #16890
Improve handling of E_DEPRECATED unhandled errors

The check_unhandled_errors_exist() function now returns the (lowest)
error type instead of true, so the caller can capture this information
to trigger a warning instead of a hard failure.

Issue #16890