Belly on the walking sprite (Platinphoenixx Add-Ons)

Pictures with the same layout and frames as the walking sprite
(mods/lewd_noita_redux/files/gfx_mina/enemies_gfx/player.png for Mina,
data/enemies_gfx/player.png for the kobold). Only draw the bulge, the rest stays empty.

  mina_belly_1.png .. mina_belly_3.png              Mina, womb fill / pregnancy stage 1-3
  mina_dress_belly_1.png .. _3.png                  optional: the dress pushed out (over the dress)
  mina_belly_<shape>_1.png .. _3.png                optional: per body shape (curvy, slim ...)
  kobold_belly_1.png .. kobold_belly_3.png          the kobold
  kobold_dress_belly_1.png .. _3.png                optional

Mina's are drawn in her base colours (the character editor recolours them like the body).
No XML needed: the game makes it at start from the walking sprite's own.
Character packs: gfx/enemies_gfx/player_belly_<n>.png (and player_dress_belly_<n>.png).
Shown from 333 / 667 / 1000 ml womb fill, or growing through a pregnancy
(setting "Visible Belly While Walking").

Stage 4 (overfull, optional): <fig>_belly_4.png (and <fig>_dress_belly_4.png), shown over 150 % full
with the extreme setting "Overfull Belly (Stage 4)". Without a stage 4 picture stage 3 stays. The same
goes for scenes: sex_layers/<scene>/belly_<fig>_4.png gets its XML from stage 3's at startup.
