Check if Record is already exclusive locked. If yes, show Form in readonly mode.

Small fix in manual.rst.

save.php, QuickFormQuery.php: fixed malformed array for JSON
Dirty.js, QfqForm.js: replace instance variable 'additionalQueryparameters' against parameter by call: optionalQueryParameters.

AbstractBuildForm.php: add variant to update md5 via form-update. Remove test 'span' wrap around 'recordHashMd5'. Introduce constants API_FORM_UPDATE_*.

DirtyTest.php: play testFormEditor.sql

Fixed broken implementation on server side.

modifiedRecord.pu: State Diagram
Dirty.php: implement $recordHashMd5 to detect modified records.
OnArray.php: new getMd5()
AbstractBuildForm.php: implemented but not working update of hidden input 'recordHashMd5'. Add hidden input 'recordHashMd5'.
BuildFormBootstrap:  Add hidden input 'recordHashMd5'.
formEditor.sql: Rename 'Dirty.recordModified' to 'Dirty.recordHashMd5'.

delete.php: process json answer of qfq-delete()
Dirty.php: More specific error message. In case of locking problem during form delete - return json and not an exception.
QuickFormDirty.php: Code cleanup. Interpret answer of dirty->checkDirtyAndRelease

Implemented: New > Close (save) now closes correctly the current page. Addtional, #1930 has been solved implizit.

AbstractBuildForm.php: Removed some unused comments. Bug fix: do htmlspecialchar_decode() always when FE_ENCODE is set to encodeSpecialchar.
QuickFormQuery.php: mv necessary systemStoreUpdate() closer to instantiating of classs Store.

Store.php: change function getNonSystemSipParam() from private to public
AbstractBuildForm.php, BuildFormBootstrap.php, BuildFormTable.php: use of getNonSystemSipParam() in deriveNewRecordUrlFromExistingSip() and createDeleteUrl()..

Manual.rst: Doc update for periodId.
DatabaseUpdateData.php, formEditor.sql: Table 'Period' and sample record.
Store.php: Implement systemStoreUpdate()
QuickFormQuery.php: call to store->systemStoreUpdate() - might solved in a better way..

Dirty.php: workaround for #4127

Save.php: replace constant

Dirty.php: save 'expire' value.

DatabaseUpdateData.php: Table Form: recordLockTimeoutSeconds - default changed from 0 to 900 secs. Existing forms get the default timeout timout interval.
Dirty.php, QuickFormQuery.php: recordLockTimeoutSeconds will be retrieved from the Form.recordLockTimeoutSeconds definition (instead of parsing config.qfq.ini). Therefore a definition per form ist possible.