B8571 Primary Key: report error if lower/uppercase don't match - in general if given primary key is not found in table definition.

Variable default: '0' is now treaten as a value. An empty string is still nothing >> no default given.

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 'pdftk' is outdated.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.

htmlid fixed to not use space, unit tests adapted

See merge request !152

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

Fix parameter name in documentation (was wrong in one spot).

See merge request !151

Add nice error message with links to skip sql functions update

See merge request !150

Release.rst: fix typo
Sitemap.rst: new created to be included by Index.rst.

Reformat Index.rst according...

See merge request !149

Reformat Index.rst according https://github.com/TYPO3-Documentation/TYPO3CMS-Example-ExtensionManual.git

# Conflicts:
#	doc/T3_DOC.md

Newdoc

See merge request !148