Replace pdftk by pdfunite. 'pdftk' is outdated. It's hard to install on Ubuntu 18. It fails for recent PDFs. 'pdfunite' is based on poppler. URLs are preserved. Orientation and size are preserved.

Fix undefined index. Refactor functions.sql to function.sql. Inplement constants for Version numbers.

Fix unit tests: replace uniqid() by uniqIdQfq() which delivers a constant id in case of running unit tests

Refs #8348 - Add header, separator and disabled menu entries. Download PDF is ok. New: '||' are required to separate menu entries.

Fixes #8116: Error-Dialog - Button for FE element is broken. First problem: replacing '\n' with '<br>' failed for FE link. Second problem: FormEditor fixed in case missing {{formId:S}}.

Fixes #8278: Bug 1 - check GET Vars but try to report problem from POST var. Bug 2: writing log message crashed due to not initialized QFQ-config.

Fixes #8067. Feature: url-sip / url-sip-skip-history - Form forwarding can now be used with SIP encoded parameter.

PDF/fileSplit: uploaded PDF file with missing extension '.pdf' have not been recognized as PDF files - fixed.