Fix several issues in the `panel.PrintMap`-class

This PR fixes several issues with the `panel.PrintMap`-class:

* When cloning the layers of the `sourceMap`, vector layers previously got special handling and would be recreated instead of being cloned; effectively this lead to loosing configured properties, e.g. a `StyleMap`. Vectors can simply be cloned, as `OpenLayers` handles the cloning of contained features for us.
* The `PrintMap` throws an error if it is being created with an `OpenLayers.TileManager`
* The examnple now also has a vector layer that shows that we can now correctly clone/print vector layers with a style map.
* dangling whitespace was removed and tabs were replaced with spaces

Fixes #217.