Many DB Updates and a few new features

Overview:
- Added the following columns to: cronjobs
    title - brief title - I need this as I have a snippet called many times and hard to tell which is which
    description - description of what job is doing easy way to document
    debug - Boolean, send to the modx error log some messages
    set_nextrun - SET('Load','Success') nextrun can be set on Load or on Success of job, this will allow a job not run forever when it fails.
    auto_clearlogs - 0 for never, Number of Minutes/age of log to clear
- Added the following columns to: cronjobs_log
    start_time - Time that job is called- logdate would be time finished
    memory_peak - Memory peak of job in MB
    status - SET('Started','Completed')
    execution_time - Caluclated time in miliseconds
- Added Indexes to: cronjobs_log   
- Added the above fields to the UI
- Added the above fields in the EN Lexicon 
- Added in try/catch for cron.php and will log error as message

Let me know if something does not make sense.

Thanks,