AutoCron.php: Fix problem with array in checkForOldJobs(). Implement check that re-trigger asynchronous cron jobs are handled correctly.

AutoCron.php: New constants   AUTOCRON_STATUS_OK, AUTOCRON_STATUS_ERROR. Status Length not limited anymore.

Manual.rst: updated to the latest autocron features.

Autocron: implement a) 'output to a file' (content of the retrived page), b) search for a pattern on the output.
Manual.rst: updated to the latest autocron features.

fixed problem with buttons clipping trough alert

See merge request !46

Error messages as modals

See merge request !45

Change getMimeType() in Report in case file is missing or `file` beaks: instead to throw an exception, an empty string is returned.