SEG 2020 and other idle fixes

[maxkazmsft]

Features

• generation of 3D output in test.py (3D segmentation maps) with geometric and arithmetic feature map averages in inline and crossline directions
• added generation of segy files for 3D segmentation images: we now have a complete 3D segy input and 3D segy output workflow
• optimized test image scoring for memory usage (no memory spikes with 3D data)
• added "memory_profiler" dependency (for optional memory profiling)
• added segy writers to write segy files based on an existing segy file (for SEG 2020 competition) and based on just a numpy array
• new BYOD script to process SEG 2020 competition training and testing data

Bugfixes

• fixed segyviewer instructions in main Readme
• fixed split ratios in BYOD scripts (correct test1 and test2 splits like in the original Dutch F3 dataset)
• fixed unet model config file to load the correct UNet module (plain UNet)
• minor tweaks to documentation and imports