* pyz: yeet the resource tar which is now pointless thanks to pkgres
* cache impresource stuff because pyz lookups are Extremely slow
* prefer tx_file when possible for slightly better performance
* use hardcoded list of expected resources instead of dynamic
discovery at runtime; much simpler and probably safer
* fix some forgotten resources (copying.txt, insecure.pem)
* fix loading jinja templates on windows
use sigmasks to block SIGINT, SIGTERM, SIGUSR1 from all other threads
also initiate shutdown by calling sighandler directly,
in case this misses anything and that is still unreliable
(discovered by `--exit=idx` being noop once in a blue moon)
