Feature #3981 / Record Locking

First version for save - not working now.
Manual.rst: document config var SYSTEM_DIRTY_RECORD_TIMEOUT_SECONDS.
QuickFormQuery.php, Dirty.php: extend to support QFQ/save().
Client.php: fixed broken PHP Unit test
Config.php: set default for dirtyRecordTimeout.
BuildFormBootstrap.php: No dirtyUrl if dirtyMode=none.
formEditor.sql: extend definition to Form.dirtyMode, new table 'Dirty'
Fixed several unit tests for new tables.