Add option to limit developer log (rolling log)

It would be nice if the developer log was a rolling log, instead of just keeping everything until its manually purged. Could add a couple of options:

1) Config option to limit the number of items in the developer log, and when it reaches that limit, it will start auto pruning old items.

2) Config option to limit by age, e.g. only keep log items that are 7 days old and prune anything older.

Or add both options 😊

On a slightly unrelated note, while peeking around the code I noticed an unused variable (I’ve seen this in various parts of EE’s code). $item is assigned a value but never used.

if (ee()->session->userdata('group_id') == 1)
  {
   $item = $logs->addItem(lang('developer_log'), ee('CP/URL')->make('logs/developer'));
  }

  $item = $logs->addItem(lang('cp_log'), ee('CP/URL')->make('logs/cp'));
  $item = $logs->addItem(lang('throttle_log'), ee('CP/URL')->make('logs/throttle'));
  $item = $logs->addItem(lang('email_log'), ee('CP/URL')->make('logs/email'));

  if ($this->search_installed)
  {
   $item = $logs->addItem(lang('search_log'), ee('CP/URL')->make('logs/search'));
  }