since it no longer is mirror_dir but `work_dir`
for status.json and custom-mirrors.json

it has been replaced by `Protocols =`
which does a better job

changed description in pacman-mirrors.conf

changed constants internal
added deleting in httpfh.update_mirrors()

add protocols filter on mirrorlist

new name and signature

corrected decision on resp_time

handle possible ftps mirrors

removed mirrors.json from `/var/lib/pacman-mirrors`
downloaded mirrors.json is saved to `/usr/share/pacman-mirrors`