add max_speed to RWInterface and update docs

    also add our Vec2d class to the local namespace in which the scripts are
    executed for convenience.
forgot to import a component copanzers/scripts.py
add an example
Merge branch 'examples'
read entity presets from files instead of hardcoding them
Merge branch 'presets'
Merge branch 'master' of github.com:ponderstibbons/CoPanzers