Fixed image cache bug: when a cache is full, a new image replaces the first cached image instead of the oldest cached image.

Latest working version of 3D imagery overlay. Unresolved errors with Google URLs for satellite imagery.

Added command to select target position for robot - command can be accessed via a right-click in the 3D View perspective --Lionel

I added the ability for the parser to pack an array of any mavlink standard type.  This will allow array types to be specified for mavlink messages without using the type="array" syntax.

I also changed how a bunch of the strings were constructed to more closely conform to the coding style guidelines by reducing the number of implicit copy constructor calls