allow placing legend outside of grid, but inside placeholder

i needed the possibility to position the legend inside the placeholder but outside the grid.
To archive this i separated insertion and aligning of the legend and added a new legend.position option.

![Screenshot](https://f.cloud.github.com/assets/1249775/2193988/7d751054-9885-11e3-96eb-65be7a0f625a.png)