Track history of tickets over time for snazzy dashboard reports

Feature/discard warning + ticket preview enhancements

Add CSV (Excel) export option to ticket search results

Adds a link to the scp/tickets.php page (Tickets) allowing for the export of
the data to CSV file. This is preliminary and still needs a few items:
  * An icon + button CSS definition
  * Support for alternate columns (staff assigned, etc.)

Also add beginnings of complex export support (PDF, JSON  and other
formats
to follow). CSV is fully supported for now.

And for brevity, add a Http::download method to allow for consistent and
browser-independent forced page content downloads

Add a %ticket_history table to track ticket states over time, correlated to
the user account changing the ticket. Then, tickets are tracked to the table
when (re)opened, closed, overdue, transferred and assigned.

UTF-8 for install

Feature/scp login design 

Support register_globals PHP ini setting from the installer

Looks good. Remember, don't close the feature branch before the pull-request in the future, so we don't have the extra commits in the pull-request.

Approved - minor edits later.

Change href definitions for embedded links in the ticket thread so that the
click will be bounced through a script. This will hide the original referrer
URL where the link originated.

Reviewed: .htaccess for mod_rewrite