zero offset when use "Spine" exporter

[songinnight2]

Spine atlas exporter offset is always 0,0
Offset should be calculated from lower-left corner.
I forked your module and wrote some additional codes.
I hope you helped a little.

exporters/index.js

let tpOffset = {
  x: item.spriteSourceSize.x,
  // *Caculate lower-left corner based offset for TexturePacker .atlas format
  y: item.sourceSize.h - (item.spriteSourceSize.y + item.spriteSourceSize.h)
};

return {
  name: name,
  frame: frame,
  spriteSourceSize: spriteSourceSize,
  sourceSize: sourceSize,
  index: index,
  first: index === 0,
  last: index === data.length - 1,
  rotated: item.rotated,
  trimmed: trimmed,
  // *Added tpOffset value to use inside .mst
  tpOffset: tpOffset,
};

exporters/Spine.mst

offset: {{tpOffset.x}},{{tpOffset.y}}