Fix #13054: Install: don't suppress errors when including libraries
Fix invalid access denied error caused by access_has_bug_level()

Commit d42e80c01277eec37c7436a23ec72073c9961c49 changed the code in
access_has_bug_level() function, and introduced a bug as the final call
to access_compare_level() inverted the 2 parameters which caused an
incorrect return value to be returned in certain cases, incorrectly
denying access to issues.

Issue #15538
Issue #15556: remove unused variable

$c_private is initialized but never used in bugnote_add()'s scope.
Documentation: added step in Customizing Status Values section

We now include instructions to check and update existing workflow
configurations to include the new status values.

Fixes #10047