Sardem

Use 0 for water missing tiles, not 1 by scottstanie in https://github.com/scottstanie/sardem/pull/16


Changelog: https://github.com/scottstanie/sardem/compare/v0.11.2...v0.11.3

Change the default watermask filename so it can be read by GDAL as a ROI_PAC file.

Allows output format/output datatype CLI arguments

- This version drops the cython code, performing and upsampling/resampling using Python or GDAL. This means that it's now a pure-python package that can be added to conda-forge and installed via conda.

- Also, the integer bounding-box shifting added in v0.10.8 was removed for consistency. The `--bbox` option will always refer to the image edges as it does in GDAL.

Assumes that a --bbox input of all integers will want the full tile

I.e. you don't need to input `--bbox -156.000138888889 19.00013888889 -155.000138888 20.000138888` to get the tile `N19W156`. You can just do `--bbox -156 19 -155 20`

Fix VRT typo causing problem for earlier versions of GDAL caught by EJFielding