get the hot nozzle out of the way before the prologue starts
avoid pushing points on the stack more often than necessary
whitespace change: updated source formatting
don't filter short fill polygons
refactoring InfillPatterns

hold currentConfiguration and layerRules in instance and removed them
from parameter lists, convert static methods to instance methods
hatch fill polygons per material
removed middleStart option
simplify calculation of infill area

* calculate how big a slice is without its borders and use that
to intersect with bridges, insides and surfaces
* simplified collection of polygons per material
* added new class Slice and let the SliceCache return that
* removed neededSlice() used by not-implemented micro layering
* removed unused argument ignoreMaterial of
BooleanGridlist.differences()
bugfix: NPE caused by cache constructing invalid Slice objects on miss
added tests for SliceCache
refactoring: only consider the needed material
moved outline calculation from ProducerStlList to Slice
removed middle man: Producer talks directly with Slice
added test for polygon simplification and fixed ...

oversimplification of a circle.
calculate infill area by substracting actual borders from total area
Finally found out how to get rid of holes in surface layers, had to ...

add more debugging facilities. Can now visualize also BooleanGrid,
BooleanGridList, Polygon in SimulationPlotter. It is now reachable
within the debugger with 
org.reprap.geometry.SimulationPlotter.getInstance().