Feature/dp modifications

Changes the ```DPBand_``` interface to a global interface called ```DPBandConfig```. 
This new interface is public and should be adapted by the banded alignment interfaces in the future. 
This would reduce the complexity of the alignment interfaces and the band parameters can be passed in their own context instead of using built-in integers. Thus, ambiguities with other parameters that might be added in the future (e.g. the current extendAlignment code) can be resolved.
The API is documented as well.