Trigger an editor after `hugo new`.

- Trigger permanently with NewContentEditor in config.{toml,yaml,json}.
- Trigger on an individual basis with --editor.
Use current working dir as WorkingDir instead of hugo executable's dir
Fix unicode menu URLs

Menu urls like /categories/новости-проекта would turn into /categories/d0bdd0bed0b2d0bed181d182d0b8-d0bfd180d0bed0b5d0bad182d0b0, which is illegal, while the directory under the categories/ is created with the original name. It results in 404 not found error.

This commit fixes that by make sure that SanitizeUrl() is called last.

Fixes #719