Updated system requirements, DOM is required since 2.9
Merge branch '2.11' into 3.0
Contao 3 only supports Internet Explorer 8
Merge branch '3.0' into 3.1
Merge branch '3.1' into 3.2
Contao 3.2 dropped support for MySQL < 5
Merge remote-tracking branch 'upstream/3.2' into 3.2.

Conflicts:
	manual/de/01-Installation.md
Merge branch '3.2' into 3.2-ja.
Catch up to 4485a8d8e8dd2c6edd5ca2193938b99863825cc9.