Merged new help content changes into the trunk. This completes the switch form DTML to STX. Also includes misc fixes to support help system.

Updated API docs, added AuthenticatedUser, ExternalMethod, MailHost,
PropertySheet, PropertySheets, Request, Response and
ZSQLMethod. (adding to trunk)...

should work again.

reinitializing the Product or I had to reinitialize the entire ZODB
sometimes.

reinitializing the Product or I had to reinitialize the entire ZODB
sometimes.

Help Content Style Guide written by Amos.

Content Style Guide.

Fixed ZCatalog constructors - there was a problem with the default argument for vocad_id that broke new catalogs.

Fixed two bugs in tutorial examples - the sample mail host is now editable, and the gadfly database setup method should now work regardless of whether a gadfly connection has been previously created.

Fixed the HTML of the ZSQL Methods 'Test' tab. Now there is an HTML doctype and the HTML and BODY tags are correct. This should probably be moved out of the code into a HTMLFile.

they already exist.