Suggest binding gnorb-org-view in Org Agenda

* gnorb.org: Add to Suggested Keybindings section
* gnorb.texi: And export
* gnorb.info: And convert
Don't let attach errors derail the trigger process

* gnorb-utils.el (gnorb-trigger-todo-action): There's something highly
  suspicious about how attachment errors affect the whole process. They
  don't actually seem to surface as full errors, but they do cancel out
  the rest of the trigger process. This may address that.
Remove process mark after bulk association

* gnorb-gnus.el (gnorb-gnus-incoming-do-todo): Users won't expect it to
  hang around.
Re-raise errors in the triggering process

* gnorb-gnus.el (gnorb-gnus-incoming-do-todo): Don't swallow them.
Fix completing-read in message disassociation

* nngnorb.el (gnorb-summary-disassociate-message): That's just not how
  it works.