Some documentation of include/auth.php.
Some documentation for include/reddav.php and a bit code cleanup.
Removed some duplicate code in RedBasicAuth and restructured a bit.
Still work in progress.
Merge pull request #616 from dawnbreak/docu

Documentation and some restructure in RedBasicAuth
New tag version of datetimepicker avoids hanging some browsers

But still won't work with those same browsers.
Devel versions seem to work, but I chose to be conservative.