support for darcs import

Hi!

In question #41438 (https://answers.launchpad.net/launchpad-bazaar/+question/41438) the support for importing from git, darcs and mercurial is raised...

In last few days I was doing lot of testing with Miklos Vajna's darcs-fast-export (http://vmiklos.hu/project/darcs-fast-export/) and now it works very nicely (although revealing some slowness of bzr's fast-import).

In the discussion of #41438 I mentioned another possible tool for incremental darcs import and that's Tailor (see (http://progetti.arstecnica.it/tailor).

So, it would be nice if you can take a look at reports in https://bugs.launchpad.net/bzr-fastimport/+bug/232177/ and provide support for incremental import of darcs repo into Launchpad so that we can host bzr branches at LP.

Sincerely,
Gour