Fixes #7603: Unit test if DatabaseUpdate() plays well. Especially that formEditor.sql is running fine.

Fixes #7594: FE.type=extra: don't name it 'type' or 'id' or 'L' - more detailed error message and an explanation in Manual.rst.

Download Excel (and all other download types): Content-Disposition header delivered/suppressed in the opposite meaning as it should be. Seems to be fixed now.

File not found in FE.type=file: Show more clearly that the pathfilename is only shown when ShowDebugInfo=on.

File not found in FE.type=file: Show more clearly that the pathfilename is only shown when ShowDebugInfo=on.

Bug 7539: Copy to clipboard not reliable. This commit fixes problems with 'copy file content' to clipboard. Refs #7539

Bug 7514. AS ..pdf|..file|..link broken defaults. Refs #7514. Fixes pdf, file. 'link' seems still be broken.

Add extension/Resources/Private/composer.json again. Makefile: add composer update again. Necessary to deliver phpoffice in extension/Resources/Private/vendor/phpoffice.