viewer: a new helper for project/check/status handlers, get_project_or_404() Also test it.

viewer: make navbar have a gradient like status badge It's better than stock navbar anyway.

viewer: generate status badge codes for embedding

viewer: add proper markup to changeset date so it's picked up by moment.js

viewer: restyle regular badges to be a bit more like status badges In practice, it means: no border, 3px rounded corners and more pronounced text shadow.

viewer: setup and clone tasks without errors/warnings are collapsed by default In addition to errors and warnings, which leave task expanded, target line also does the same, so sharing a link to a specific line doesn't surprise people by hiding the line somewhere.

incoming: remove linkstart and linkend until things are actually ready

tests: test read_linter_config() from checker.py

tests: test run() from checker.py

incoming: save linkstart and linkend for lines (not used yet)