Walk Python value more gently to C string.
Allow update of nodatavals in r+ mode.
Merge pull request #169 from mapbox/issue167

Allow update of nodatavals in r+ mode.
Closes #167.
Added support for additional data types and mask in sieve function
Added support for running test coverage with coveralls
Merge pull request #170 from brendan-ward/issue159

Added support for additional data types and mask in sieve function
Merge pull request #171 from brendan-ward/test_coveralls

Run code coverage analysis with coveralls
Add coveralls badge.