EZP-21143: Allow not executing pagelayout.tpl when using an eZ5 layout

Allow users of ezpkernel to avoid executing the pagelayout when calling run().
Useful f.e. when in eZ5 context and using an eZ5 pagelayout

Closes #668
Fix EZP-20949: Additional checks for correct object type in version and node class
Fix EZP-21150: Sql parameter not implemented in runcronjobs
EZP-21150: Clarified --sql option usage in runcronjobs.php
Merge pull request #677 from ezsystems/EZP-20949_additional_fix

Fix EZP-20949: Additional checks for correct object type in version and ...
Fix ezp-21121: runcrojobs.php -s always prints warnings