* Documentation

** DONE user documentation
** DONE update how to write backends
** DONE update introduction to code

* Org-sync

** TODO write tests
** TODO better error checking
** TODO convert markup to org-mode and reciprocally
Also, find out how to handle charsets, line-ending, etc.

** DONE use usual deadline timestamp from org-mode
No backend uses it but importing from/exporting to org-element works.

** TODO fix date representation
** TODO better auth system
Some ideas:
- a single variable maps repo urls to user accounts.
- each backend use its own variable, more flexible.

** DONE cache parse/fetch result
os-cache-alist maps urls to buglists and each buglists has a
=:date-cache= property.

** DONE replace overridable macro by something simpler
The right value of a pair in os-backend-alist is now the symbol of a
variable defined in each backend. This variable is an alist that maps
verb symbol (base-url, fetch-buglist, send-buglist for now) to
function symbol.

* Backends
Write backends for some free software.

** Redmine
*** TODO basic syncing

** Bugzilla
*** TODO basic syncing

** Github
*** DONE basic syncing
*** DONE tags
*** TODO milestone

** Bitbucket
*** DONE basic syncing
*** TODO component
*** TODO version
*** TODO milestone
*** TODO test DELETE