QDoc: Clean up whitespace

Ensure that QDoc conforms to Qt style, whitespace edition.
For the most part, the change involves moving the pointer operators.
Also remove whitespace following an opening parenthesis, or
immediately preceding a closing one. In some cases, adjust the
following line accordingly in methods that span multiple lines.

Change-Id: I56ae125a2acf09c669c0a73dc814d05f13575f39
Reviewed-by: Martin Smith <martin.smith@qt.io>