Segysak

Added `get_affine_transform` to `.seis` for plotting and data transforms.

CLI Converter now handles multiple file input and output with internal for loops.

Bug fix to force header output to fit int32 in SEGY
Conversion of documentation to py files and added IPYNB download to docs.

* Fixes to 2D loaders.
* Support for float (sub integer) values on vertical axis.
* Experimental support for ZGY - requires manual install of openZGY.

Back port of v0.3 features primarily for `segy_writer` but also including some updates to docs and bug fixes.

Patches for segy_writer and docs.
- segy_writer function for 2d, 2dg, 3d, 3dg writing
- updates to docs
- contribution and coc guides
- bug fixes

End Transform 2020

Add arbline extraction.
Fixed export for 3D SEG-Y
Improved Documentation and Examples