Throttle modules interface moves to throttle settings

Rework of merlinofchaos's original patch to move the throttle module settings to throttle.module.
Changes: Checking enabled modules from all modules retrieved by module_rebuild_cache to use .info file descriptions.
Removed '#suffix' from hidden fields as required modules are not displayed.
Added comments.

This patch only has the new additions to throttle.module and does not attempt to remove anything from system.module which will be accomplished by this patch: http://drupal.org/node/81631

Rerolled to head since dependencies got committed: http://drupal.org/cvs?commit=41680
Removed throttle functionality from system.module.

I started implementing the dependency checking and then remembered a discussion we had when implementing the dependency system.
Excerpt from that discussion: http://drupal.org/node/81631#comment-133827

...Basically, this dependency system allows modules to announce what other modules *they will probably crash without*. Undefined function calls, etc....

Correct me if I am wrong but the throttle system only disables certain cpu intensive functionality when webserver load gets too high and does not physically remove the module from the system. If we define the dependency system as modules that cannot work because of methods exposed by other modules then I do not see how throttling a dependency will have much affect on an unthrottled dependent since it still has access to the throttled module's methods for it is still installed on the system and its files are still included by drupal. Please advice...

Rerolled to fresh head...
Send description through t();
Change displayed name to $file->info['name'] instead of filename.
Fix theming to make displayed table look the same as the modules table.

Please nit pick...