Reject invalid urls in linkchecker
Reject invalid urls in linkchecker

For example root-relative links will now be rejected.

Also remove some exceptions which have since been fixed and fix a typo in
the broken redirect handling.

aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust