Adding setNumId method for ListItem style

[eweso]

Description

By allowing to set the numId in the ListItem style manually, you can separate lists. Every ListItem with the same numId belongs to one list. This allows you to restart list counting. For example:

addListItem("tem 1", 0, ['listType' => 7, 'numId' => 1]);
addListItem("tem 2", 0, ['listType' => 7, 'numId' => 1]);
addListItem("tem 3", 0, ['listType' => 7, 'numId' => 1]);

// restart list
addListItem("item 1", 0, ['listType' => 7, 'numId' => 2]);
addListItem("tem 2", 0, ['listType' => 7, 'numId' => 2]);
addListItem("tem 3", 0, ['listType' => 7, 'numId' => 2]);

Fixes # (issue)

Checklist:

• I have run composer run-script check --timeout=0 and no errors were reported
• The new code is covered by unit tests (check build/coverage for coverage report)
• I have update the documentation to describe the changes

[eweso]

I have still problems in using GitHub. I hope, that my pull request now worked...

[tobibuenter]

what's the state here? We have problems with restarting numbering levels (even "restart" => "newSection" is set)...