link 6.x-2.6-beta1

This is a beta of the changes that have been sitting in the release queue for a while, plus the changes which I applied to the project tonight:

#370195 by grendzy. Ensure content.module runs its update first.
bug report #318277 by quicksketch, recidive: set fields created by drupal 5 to nullable.
task #438756 by jcfiala: Bring link module to Drupal standards.
Changing widget name to just "Link".
#328607. Plain formatter omits query strings and named anchors when printing URLs.
#278180: ll user to choose link target
bug report #436020 by David_Rothstein: Allows .asia as valid domain.
bug report #436020 by joshuajabbour: Allow exclamation mark in URL, as per RFC 1738.

Assuming I don't notice any problems with this in a short while, I'll make it an official release.