Add convenience macro for fast connects in declarative.

Add convenience macro for fast connects in declarative.

We already follow this pattern several places, so
this commit creates a convenience macro for it, and replaces
previous usage where appropriate. Also adds the macro
several places as further optimization.

Change-Id: Ieff5ed6cc51c34d0a1c8aa42ac40314ea243477a
Reviewed-on: http://codereview.qt-project.org/5342
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>