[C] Vehicle Player teleport. Fixes BUKKIT-3341

The Issue:

Players who are sitting inside a vehicle, wont be teleported if you use the teleport(Location) Method.

Justification for this PR:

Fix the bug.

PR Breakdown:

Simply call the leaveVehicle() Method in the teleport(...) Method when entity vehicle is not null.

Testing Results and Materials:

Just tested on my Test Server. This is not the biggest change, so i don't think a big test is recommended :P

JIRA Ticket:

BUKKIT-4243 - https://bukkit.atlassian.net/browse/BUKKIT-3341