Manual.rst: Best practice default values.

Manual.rst: usage of drag and drop.

DragAndDrop.php, QuickFormQuery.php: bug fixes
FillStoreForm.php: no FE on a Form now ok - necessary for dnd sort forms.

Html2Pdf.php: remove check if wkhtmltopdf is executable - without the check, it's possible to specify variables, like LD_LIBRARY_PATH, in front of the executable. The latest development version of wkhtmltopdf needs specific libssl and libcrypt libs.
Manual.rst: add a note the the latest wkhtmltopdf can be requested from the QFQ team.

New Version naming scheme: <yy>.<mm>.<index> - e.g.: 18.04.1
ext_tables.php: path to icon fixed

Manual.rst: New check list. Updates on missing config entries. Details for record locking. More precise extraButtonInfo explanation.
config.qfq.example.ini: small updates to explanations.
ext_conf_template.txt: First version of extension manager configuration setup. Not functional.

AutoCron.php: allow https connections with invalid certificate (e.g. 'localhost' is not listed as a valid hostname).
Manual.rst: Enhance best practice to setup AutoCron.

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.