Write ns and interval in SEGY trace headers by default

S-01549

As a Tullow Geophysicist I want to ensure ns and the interval in each trace header matches the binary header for reasons of consistency, particularly during concatenation.

WriteSEGY should set the ns and interval on each trace header to match the binary header in it's write* methods. ExSeisDat doesn't support per-trace ns and interval. The documentation should be updated to make this clear.

PreDev Notes

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Implementation Notes:

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System Test Changes:

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Bug Fixes:

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C++ API Changes:

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C API Changes:

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Success Criteria:

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CREATED ON - 21/11/2016