Fix core part of Mac crash.
Fix core part of Mac crash.

Calculations in the limited beading meta strategy relied on the assumption that the overall requested bead count would be equal to any parent strategies' returned toolpath ammount. This commit resets the bead-count each time the parent is 'consulted' for the entire initial return value.

CURA=7914

Ultimaker/CuraEngine,Ultimaker/CuraEngine