Planning/Measusrement plugin

This is the fully implemented version of planning and measurement submitted for inclusion in early 2012. It has been updated to the latest plugin format and fully integrates into the base menu structures. It should be used to replace the current Calculate Distance plugin, which was a partial implementation of the original proposal using the plugin format.
The original implementation was operationally tested as a GPS and planning tool for 2 months during a motorhome holiday in several European countries and the features were extremely valuable, particularly the display zoom and planning-track save/reload.
There is a change required in OsmAnd that is subject to another pull request.