Refs #582: Don't need to do $req construction to merge parameters unless you're using get. POST can accept raw values
Avoid clobbering messages; $vars['messages'] is already set by pageDraw()
Handle API returns in a more meaningful way.

When called as an API, post results will:

* Default forward() to / is disabled
* If postContent() returns nothing (null) then we
** Set a 400 response
** Set an error message if no messages have been set
* If postContent() returns something then
** if it's ===false we set 400
** We return the result in the current template

Closes #584
Refs #584: Handle delete and put like post
Closes #587: Default xxxxContent() methods set 501 Method Not Implemented.

Closes #588, since it includes those patches as well
Minor comment change
PuSH tweak
New event hook in page head
Better feed config item
PuSH headers on HTTP resources
Default PuSH hub
Simplified hub
Moved webmention HTTP headers
Corrected PuSH HTTP headers
Closes #346: Show last post time not the updated timestamp of the actual user object (Which is rather misleading)
addMessage() -> addErrorMessage()
addMessage() -> addErrorMessage()
addMessage() -> addErrorMessage()
addMessage() -> addErrorMessage()
addMessage() -> addErrorMessage()