javascript error reporting interface

#1419652: JavaScript logging and error reporting

This patch adds a Drupal.log(message, type) function that wraps around the console object and falls back to alert for retarded browsers.
Types available are the same as in drupal_set_message(), each is mapped to the relevant console method: status is console.log(), warning is console.warn() and error is console.error(), unknown types just add a 'mycustomtype: ' prefix to the message.

I'm using values from error_level to choose which error to display with a catch

• ERROR_REPORTING_HIDE displays nothing,
• ERROR_REPORTING_DISPLAY_SOME (which is called Errors and warnings in the admin form) only displays warnings.
• ERROR_REPORTING_DISPLAY_ALL All of the above plus errors.

There will be changes to make to this patch but i'm not sure at which level, I need some help integrating this properly. I'm not talking about a watchdog interface there are other issues for it.