Optimize file write

[brianhendee]

When performing a SICD write, Sarpy stores the data in an array, then creates a bytes object from that array. That takes time, and increases the memory footprint. This modifies the logic to create a view into the stored array instead of a copy. It also allows memory mapping to be explicitly turned on and off. This prevents sarpy from attempting to use memory mapping on systems that don't support it.

[petersontex]

@brianhendee Thank you for your code submission. We are reviewing the code and determining when to integrate it. We are also writing test cases to ensure proper integration.

[petersontex]

@brianhendee I am reviewing your code for integration into a sarpy release. How did you envision users activating this enhancement? It appears to me that users set all the parameters used with the NITFWriter in the NITFWritingDetails class. What do you think of moving the in_memory parameter into the NITFWritingDetails class?