WebSubmit: check for record-submission connection

• Adds new parameter to Set_RN_From_Sysno function: record_search_pattern. If this parameter is set, the Set_RN_From_Sysno function will check that a certain record can be handled by the current submission (modified, deleted, etc).

• Ensures that Set_RN_From_Sysno function refuses to proceed with deleted or non-existing record IDs. Cast sysno to int (stop workflow if not possible).

• Explicits in Get_Recid documentation that 'record_search_pattern' parameter does not apply when retrieving recid from cache ('SN' file).