Views random seed

Adds a random views order handler with a seed.
The seed value is generated based on the current timestamp, which is used as the seed value, producing a repeatable sequence of column values. This makes it possible to have paging and not have items show up twice.

Seed value can be flexibly configured per view display to expire after a predefined time or a custom number of seconds, or reused from another view display.

Configuration:

1. In the View's Sort criteria, add the "Random seed" sort plugin.
2. In the plugin settings, you can reuse a seed from another View display using "Reuse seed from another view display".
3. Configure the "User seed type" and "Reset seed" options as needed.

More info:
- MySQL: http://dev.mysql.com/doc/refman/5.0/en/mathematical-functions.html#funct... about RAND() and the optional integer argument.
- PostgreSQL: http://www.postgresql.org/docs/current/interactive/functions-math.html about RANDOM() and the 'select setseed' function.