Clarify ord() and chr() documentation
Issue #20184: Add signature introspection for 30 of the builtins

Also adds a test to test_inspect to track progress on builtin
introspection support, to ensure it doesn't regress in the future.
Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.
Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.