Refs #7634. Session Timeout zu kurz. Add logout of FE user. Logout happens not directly on the first call, but on the second or third page access.

B7634. Fixes #7634. Session Timeout zu kurz. The bug was probably not a bug, but a too short timeout together with an misleading exception (logout and in - but reload the page also leads to valid page). The fix is 'take the system default (php.ini) and set that one'.

Fixes #7864. 'required'-FE Elements, deactivated via formModeGlobal=requiredOff, now gets class 'required-field'. The final 'required' mode is still temporarily disabled.

Bug: die Hashes aendern sich jedesmal - einloggen mit dem neuen PW ist nicht moeglich

This reverts commit d2054269

Rewrote some doc. Extend sql commands to be recognized in QFQ vars (have been already subscribed in that way in Manual.rst).

Fixes #6914. Final implemention of customized typeMessageViolation. Incl. unit tests. New escape mode 'C' - escapes ':' by '\'.' - useful for variables in variable definition.