Task-number: QTCREATORBUG-2674

Reviewed-by: hjk

This is basically for consistency with the docs and with the html
extraction mechanism.

Reviewed-by: Roberto Raggi

This is actually a general improvement that splits the qualified names
so more help ids candidates are considered when searching in the docs.

Reviewed-by: kh1

Tooltips can still be improved.

Task-number: QTCREATORBUG-2330

Hierarchy information removed from tooltips now.