Use the improved login function
Redirect to ticket view on successfull login.

* No longer redirects - simply returns usersession obj.
* support error setting - shown on login page in place of "Authentication Required";

change tryLogin to simply login

Imrove internal notes posting
Improve ticket assignment & alerts

 e.g %{staff.*} can be overwritten by a string (placeholder) as assign('staff', 'SYSTEM').

Improve variable's preg_match_all (Thanks to Jared)

Reviewed-By: Peter Rotich <peter@osticket.com>

Self merging.

Feature/new scp icons

Reviewed-By: Peter Rotich <peter@osticket.com>

Feature/client side less

Don't migrate attachments as part of the 1.6* major upgrade. Wait unit
transitioning to schema signature dd0022fb, where the new table for
file_chunks is created.

Incremental developers will already have the columns dropped from the
%ticket_attachments table and will receive an error for the cleanup script,
but the upgrader is configured to ignore errors from the cleanup scripts.