added function for quickly reprojecting GeoArray to a given pixel grid; mask_nodata is now a subclass of GeoArray

geo.coord_grid:
- snap_bounds_to_pixGrid(): added docstring

io.raster.GeoArray:
-GeoArray:
    - bandnames getter: bugfix for not checking if shape of GeoArray.arr changed
    - mask_nodata setter: now sets mask_nodata to a subclass of GeoArray 'NoDataMask'
    - __getattr__(): now also returns results of functions belonging to np.array instances
    - calc_mask_nodata(): changed data type of nodata mask to np.bool
    - save(): bugfix for wrong metadata keys
    - added reproject_to_new_grid(): function for quickly reprojection all array-like attributes to a given target grid
- BadDataMask:
    - bugfix for not allowing certain pixel value combinations
added class NoDataMask

updated __version__