Include QDataStream.

Don't rely on it being pulled in by other includes.

Change-Id: Ifda86c1a5b3e76299594fafbbb6d2d94f24b0bb3
Revert "Fix compilation after the qml engine changes"

This reverts commit cf2e367180d75a5591143e77b9173f13adb9e8e6.

Conflicts:
	src/imports/location/location.pro
	src/imports/location/qdeclarativegeoroute.cpp
	src/imports/location/qdeclarativegeoroutemodel.cpp
	src/imports/location/qdeclarativegeoroutesegment.cpp
	src/imports/location/qdeclarativepolygonmapitem.cpp
	src/imports/location/qdeclarativepolylinemapitem.cpp

Change-Id: I5179ed4c182047e6bb8b2466c366d9f6538000a4