Version 0.4.1

Add `step` parameter to value decoding in the deckgl map (#300)

* Initial 2d hillshading iteration.

* Use separate shader for colormap, like the hillshading

* Clear depth in minimap

* Add value decoder params

* Add missing newline

* Add hillshading in the python example

* Merge valueDecoder object with defaultProps

* Add step parameter to value decoding