docs: Remove broken link
local: Make browse test check ordering again
ext: Disable extension if a dependency isn't of the correct version

Fixes #657
log: Don't filter anything at all on the root logger itself
log: Use custom filter to implement verbosity levels

...instead of hooking handlers onto multiple loggers with disabled propagation
from those loggers to parent loggers, breaking alternative log methods, like
custom setups through the the logging/config_file config value.

Fixes #661
log: Make other logging work when logging/config_file is in use
docs: Update changelog
Bump version number to 0.18.1
docs: Update changelog for v0.18.1
Release v0.18.1
Merge tag 'v0.18.1' into debian

Release v0.18.1
debian: New upstream release
debian: Adjust log format
debian: Remove local/tag_cache_file config value
debian: Create local/data_dir directory