extracted pattern of infill to new interface

only implementation does rectilinear infill, replaces even/odd hatch
direction
removed valve parameters
removed parameter RepRapAccelerations (and SlowZFeedrate)
removed parameter 5D
cleaned up retraction
removed cooling stuff
simplified Integer2DPolygon
moved outline and infill speed parameters to PrintSettings

as perimeterSpeed and infillSpeed.
have distances in preferences instead of ...

... delays for retraction and extra lengths at layer/polygon start.
* Removed extrusionSpeed (was misleading, never used for actual
extrusion).
* Removed separation flag (was also never used for actual extrusion).
* Removed setMotor, subsumed by startExtrusion (renamed from
setExtrusion).
removed unused SlowXYFeedrate
moved StartRectangle to PrintSettings as skirt
moved brimLines to PrintSettings
moved shield to PrinterSettings
bugfix: when insideOut option is true, revert only ...

... the order of the just calculated grids, not the complete result
(that contains already some other grids).
added boolean preference "Support" to PrintSettings
moved FoundationLayers to PrintSettings (as raftLayers)
moved Debug to PrintSettings (as verboseGCode)
moved SupportMaterialType to PrintSettings as supportExtruder