Adjust rewrite rule generation for podcast episodes, respect rule order, fixes #468
Merge branch 'master' into release-1-10-17
update readme
fix cache concurrency issues via 24h auto-expiry

“fix” is a bit of a hyperbole here but it’s good enough. Temporary
display bugs can only occur when a plugin is used that replaces the
database as a storage engine for transients.
change cache namespace to avoid legacy cache bugs
version migration: delete legacy caches
bitlove: add feedproxy warning