Added safeguard so that if more than 200 chain ends are found, it stops looking for chains.
Added safeguard so that if more than 200 chain ends are found, it stops looking for chains.

So now, if the first time through the chain finding code it detects that there's very many
chains, it just gives up looking for them so it should never get stuck here doing too
much work looking for all those chains.

The 200 limit should allow most models to be processed optimally. Complex skin areas filled with
zigzag lines are likely to bust the limit.

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