* Optional offset and count added on client level

* Rpc interface extended

* Tests corrected

* Filtering code refactored a little bit

* Offset type was changed to usize

* Handling of block hash in offset added

* Offset reworked to number

* Trailing comma removed

* Import for Quantity type added

* Offset and count moved into filter object

* Lost comma removed

* Return empty vec instead of None in case of incorrect range