Test if using a NullPool for db connections helps db issues.
Add an urlrewriter for the koreus site

It was copied/pasted from the urlrewrite_deadfrog.py file and adapted.

It rewrite the url from the koreus rss entry to the download url from the
download page.
Prepare v1.2.242.dev
Merge pull request #403 from Flexget/nullpool

Test if using a NullPool for db connections helps db issues.
Merge pull request #404 from Konubinix/develop

Add an urlrewriter for the koreus site
UrlRewriter nyaa now supports new categories, default changed.

- anime eng (new default)
- anime raw
- anime non-eng
v1.2.242