Map "error" and "out of range" values to None

[vesuvisian]

The ST0601.11 standard provides for certain "error" and "out of range" values (see for example Sensor Latitude in the table on page 17). These values currently trigger ValueErrors when the library attempts to parse them. This PR proposes instead to map them to a value of None.

*This is my first time attempting to contribute to anything public, so apologies if I'm doing it wrong or stepping on toes.

Fix issue #40

[All4Gis]

Thanks, Can you fix the pipeline?Only add default value in this line:

def float_to_bytes(value, _domain, _range, _error):
to :

def float_to_bytes(value, _domain, _range, _error=None):

[vesuvisian]

Okay, I've now updated float_to_bytes as you requested.