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>
Reject negative number of alternative routes.

Requesting a negative number of alternative routes does not make sense.
Fall back to the default value of 0 if a negative number of alternative
routes is requested.

Change-Id: Iecc1b7ba8bfa25b59b2a4c2efeafa33fd528377d
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Fix QGeoRouteXmlParser test.

The TravelTime element is a double, which was failing to be parsed by
QString::toInt(). Fixed by using QString::toDouble() and rounding the
result.

Change-Id: I012c277f1efdb3811a50eff96519a4d0d9959a67
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>