Issue #632080 by donquixote, mathieu, jonhattan, andypost: clone return values from _system_theme_data(), so modules careless about lack of object copies will not overwrite the system level cached values

#147000 by pwolanin, mikeytown2, et. al.: avoid multiple, parallel rebuildings of module and theme data

#245990 by David_Rothstein, Pedro Lozano, andypost: do not follow any redirections in system_check_http_request() since we only need data on whether HTTP requests worked at all

#528204 by rfay, drewish: menu item sorting should be case insensitive; lowercase titles for sorting

#193366 follow up (rollback) by Anthony Hersey, Senpai, moshe weitzman: remove all cache clearing feature of the system module listing page; instead point to the performance page where we have a dedicated button for this; the trick caused lots of issues with speed

#228971 follow up by drumm: forward port -2.5h timezone from Drupal 5, made time zone list consistent with Drupal 5

#228971 by maq0r, JuliaKM: as of December, 2007, Venezuela is GMT/UTC-0430, but that timezone was not in the list of our supported zones

#489762 by JohnAlbin: include subtheme and base theme list with processed theme .info file data; prerequisite to improve theme security and fix a possible WSOD on theme selection

#245990 follow up by Damien Tournoud, David_Rothstein, pwolanin: Move back to an internal URL check for HTTP request checking and make the request checking less intrusive on what requests can be accomplished

#245990 by Dave Reid, chx, dww: Look for the www.example.com page when a HTTP request seems to fail. Looking for the local page caused problems for people with interactive authentication, redirects, hosting added JavaScript code, and so on.