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.

Dirty.php: add comments. Add timeout checking

file.php, load.php, Html2Pdf.php: minor updates.
Dirty.php, QuickFormQuery.php: optional $lockTimeout as parameter during instantiating. Return $lockTimeout where necessary. Otherwise read qfq.config.ini. Refactor process(), acquireDirty(), checkDirtyAndRelease().

Dirty.php: record delete is handled - if lock exist, delete is not allowed.

Dirty.php, QuickFormQuery.php: Update user messages. Renamed releaseDirty() to checkDirtAndRelease()

Manual.rst: add documentation for record locking
DatabaseUpdateData.php: Add new column 'dirtyMode'
Dirty.php, Config.php, formEditor.sql: remove dirtyMode=readonly. Rename 'timeout' to 'exclusive' and 'overwrite' to 'advisory'.

Add Message if dirtRecord is missing.

Fixed some 'unknown index' issues - deny save in a first version works.

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.

typeahead.php: An exception catched in typeahead.php has been assigned as array element, instead of a whole array. Fixed.