Re-arrange batch system front-end to match Web UI behavior
* autoswap time and idleswap time defaults are inherited from the associated sitevars. - "general/autoswap_threshold", and "idle/threshold", respectively * autoswap default state follows associated sitevar ("general/autoswap_mode"). * Any user-requested autoswap duration is checked against the "general/autoswap_ max" sitevar. - Admins can override. * Any user-requested idleswap duration is checked against the "idle/threshold" sitevar. - Admins can override. * Disabling swapping (-S option) is prohibited, except by admins. * Removed all special-case checks for requests coming via the XMLRPC server.