LP#1332138 Report template / field documentation

LP#1332138 Report template / field documentation

* Report templates support a new External URL field, which may
  contain a link to template-specific, local documentation.

 ** When set, a link to the external documentation will be
    displayed in a new column in the template list and within
    the report editor.

 ** URL's are set in the 'Documentation URL' entry.

* Template display fields and filters support a new Field Hint
  value.  When set, hints are displayed in the report editor.

 ** Values are set via the 'Change Field Hint' option along
    the bottom of the template editor.

------ from commits ----

* Initial template-level support for inline template and field documentation
* Use external documenation url in clark output
* Show the docs link and strings in the report editor
* Set the href of a link, instead of the text content of a span
* Attempt to pop up a new window (may require more pushups in the XUL staff client)
* Add calculated column support, use it for external docs url
* Realign field names

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Kathy Lussier <klussier@masslnc.org>
Signed-off-by: Ben Shum <bshum@biblio.org>