Implement terrain formats from HE1

[blueskythlikesclouds]

• Packed File Info (*.pfi)
  • Read
  • Write
• GI Texture Group Info (gi-texture.gi-texture-group-info)
  • Read
  • Write
• GI Mip Level Limitation (gi-lim.gil)
  • Read
  • Write
• Light Field Tree (light-field.lft)
  • Read
  • Write
• Terrain (terrain.terrain)
  • Read
  • Write
• Terrain Block Sphere Tree (terrain-block.tbst)
  • Read
  • Write
• Terrain Group (*.terrain-group)
  • Read
  • Write
• Terrain Instance Info (*.terrain-instanceinfo)
  • Read
  • Write
• Visibility Tree (visibility-tree.vt)
  • Read
  • Write
• Meta Instancer (*.mti)
  • Read
  • Write