Fix crash in tile fetcher when no engine is set.

The engine is stored in a QPointer. The pointer must be checked for
validity before use.

Change-Id: I07eaf9276511273735f000ce0eb9cdf2fe130df3
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Nokia plug-in URL and tiler API updates

Updated URLs for places and map tiler to current ones. Added URL
management for additional hosts for hybrid, terrain and satellite maps.
Added new languages and map types available in the new tiler API.

Bug fixes for code evaluating copyrights text to show. Now only
copyrights related to viewed maps are shown and each name is shown only
once.

Updated drawing of copyright information to show HERE logo and
copyrights text side by side. This is to avoid having logo jumping
up and down.

Change-Id: Ide18a95335c4299c8219c4dbcfb0cc60b43d46c3
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Report direction and vertical speed with Geoclue plugin.

Geoclude provides both direction and vertical speed information with
the velocity interface. These values were previously being ignored.

[ChangeLog][QtPositioning][Geoclue] The Geoclue plugin now reports
direction of travel and vertical speed attributes, if supported by the
active Geoclue provider.

Task-number: QTBUG-36298
Change-Id: I9f99a64f3c2bd78a06a6c60e0ef3af6f75223e9f
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Attempt to crash in tile cache.

The tile cache can sometimes end up with null pointers which causes a
crash when saving the state of the cache queues to disk. Fixed by
skipping over these entries.

Task-number: QTBUG-36486
Change-Id: Ifa359bd1f9dbe37da0d5b208a7c4ee7a26f8bd44
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>