LP#1410369: add a new view to restrict arbitrary editing access

LP#1410369: add a new view to restrict arbitrary editing access

The previous commit now allows owning_user in fm_IDL.xml to
specify that patrons can access their own messages, saving
the need to write some copy-and-paste middle-layer code.

However, we don't necessarily want a patron who figures
out how to use pcrud directly to change the content
of messages that are sent to them.  To avoid that, this
patch adds a new view, actor.usr_message_limited, that is
allows updates of the read_date and deleted columns in
the underlying table, but nothing else.

This patch also fixes a couple typos.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>