QUrl: add NormalizePathSegments to UrlFormattingOptions

This is a bit like QDir::cleanPath(), but for URL paths.
The code is shared with QDir::cleanPath(), by extracting the common parts
it into a helper, qt_normalizePathSegments().

Change-Id: I7133c5e4aa2bf17fba98af13eb5371afba64197a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QUrl: remove old commented out code for normalized().

adjusted(NormalizePathSegments) does this.

Change-Id: I4b17c39174b5c04edac8d51e5fef8cd052db4b3f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>