WarpOp boundMode parameter.

* Added bindings for the WarpOp's FilterType parameter's enum values.

* Added the BoundMode parameter to the WarpOp:
The new parameter specifies how out-of-bounds pixels are sampled from the input image. A new option "SetToBlack" has been added which sets pixel samples that are out of bounds to black.
The default value is set to "Clamp" to ensure backwards compatibility.