Alpha blending of child sprites incorrect

[ihfdayton]

Any sprite that is the child of another demonstrates strange transparency artifact around the edge of the sprite. This is most noticeable in menus, particularly the options menu.

Essentially, the child sprite "cuts through" the parent object, showing the world behind instead of blending with the parent color.

Strangely, this only happens around the immediate edge of the sprite (perhaps where alpha isn't 0 or 1?).

Possible issue with discarding fragments prematurely in Sprite shader?

[playmer]

Mostly fixed by: #173