Dressup to add dragknife corner actions to a path

Dragknives have an offset so paths must be extended to complete the cut.
They also require special handling if the incident angle between two segments
is small.  This dressup provides properties for the filter angle, offset
distance, and pivot height.  One known area still needs to be addressed:

If the segment being processed is shorter than the offset distance, the
extension may be added incorrectly.

Additional corner strategies could also be added in the future to enhance drag
knife performance.

Some of the files also got a pep8 cleanup.

PathKurveUtils:  logic around line #460 to always pass Z value.
Previously, the Z was only passed if it changed.  This caused some downstream
problems for dressup functions.

Changes to Dressup so it works with parent objects correctly.

src/Mod/Path/PathScripts/PathUtils.py

@@ -25,11 +25,13 @@
 import FreeCAD
 import Part
 import math
+import Path
 from DraftGeomUtils import geomType
 from DraftGeomUtils import findWires
 import DraftVecUtils
 import PathScripts
 from PathScripts import PathProject
+import itertools
 
 
 def cleanedges(splines, precision):
@@ -120,6 +122,29 @@ def segments(poly):
     ''' A sequence of (x,y) numeric coordinates pairs '''
     return zip(poly, poly[1:] + [poly[0]])
 
+def is_clockwise(obj):
+    '''tests if a wire or Path is clockwise'''
+    sum = 0
+    if isinstance(obj, Part.Wire):
+        for first, second in itertools.izip(obj.Edges, obj.Edges[1:]):
+	    sum = (second.Vertexes[0].X - first.Vertexes[0].X) * (second.Vertexes[0].Y + first.Vertexes[0].Y)
+        sum += (obj.Edges[0].Vertexes[0].X - obj.Edges[-1].Vertexes[0].X) * (obj.Edges[0].Vertexes[0].Y + obj.Edges[-1].Vertexes[0].Y)
+    elif isinstance(obj, Path.Path):
+        movecommands = ['G1', 'G01', 'G2', 'G02', 'G3', 'G03']
+
+        lastLocation = {'Y': 0, 'X': 0, 'Z': 0.0}
+        currLocation = {'Y': 0, 'X': 0, 'Z': 0.0}
+        sum = 0
+
+        for curCommand in obj.Commands:
+
+            if curCommand.Name in movecommands:
+                lastLocation.update(currLocation)
+                currLocation.update(curCommand.Parameters)
+                sum += (currLocation["X"] - lastLocation["X"]) * (currLocation["Y"] + lastLocation["Y"])
+        sum += (0 - lastLocation["X"]) * (0 + lastLocation["Y"])
+
+    return sum >= 0
 
 def check_clockwise(poly):
     '''
@@ -352,6 +377,12 @@ def SortPath(wire, Side, radius, clockwise, firstedge=None, SegLen=0.5):
     sortededges = Part.__sortEdges__(edgelist)
     newwire = findWires(sortededges)[0]
 
+    print "newwire is clockwise: " + str(is_clockwise(newwire))
+    if is_clockwise(newwire) is not clockwise:
+        newwire.reverse()
+
+    print "newwire is clockwise: " + str(is_clockwise(newwire))
+
     if Side == 'Left':
         # we use the OCC offset feature
         offset = newwire.makeOffset(radius)  # tool is outside line
@@ -362,6 +393,9 @@ def SortPath(wire, Side, radius, clockwise, firstedge=None, SegLen=0.5):
             offset = newwire.makeOffset(0.0)
         else:
             offset = newwire
+    print "offset wire is clockwise: " + str(is_clockwise(offset))
+    offset.reverse()
+    print "offset wire is clockwise: " + str(is_clockwise(offset))
 
     return offset