Model trainer: North/South comprise the Z axis in the source data

Dependencies

• [2] 5AMZXFS5 model trainer: function to generate inputs to pass neural network for rendering equirectangular projection
• [3] 6AXPZL5P Try to offload tight loop to rust (for now it segfaults)

Change contents

• replacement in trainmodel/src/helpers.rs at line 115
  [2.1170]→[2.1170:1261](∅→∅)
  − target[pixstart + 1] = yrs * xr.cos();

  − target[pixstart + 2] = yrc;
  [2.1170]

  [2.1261]
  + target[pixstart + 2] = yrs * xr.cos();

  + target[pixstart + 1] = yrc;