Extend processHoleInsets() so that it can handle multiple level 1 insets adjacent to a hole.
Extend processHoleInsets() so that it can handle multiple level 1 insets adjacent to a hole.

Previously, it just handled a single level 1 inset next to a hole but now it can cope
with more than 1.

Ultimaker/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine