Introduce markers py, and the first marker (empty shape)

latticeMarkers.py

@@ -0,0 +1,35 @@
+import Part, os
+
+__title__="latticeMarkers module for FreeCAD"
+__author__ = "DeepSOIC"
+__url__ = ""
+__doc__ = "Module for loading marker shapes for Lattice workbench"
+
+_nullShapeShape = 0
+
+def getShapePath(shapeName):
+    """
+     getShapePath(shapeName) converts marker file name without path 
+     to a full path to a file. shapeName should be a file name with 
+     extension, for example "empty-shape.brep"
+     """
+    return os.path.dirname(__file__) + os.path.sep + "shapes" + os.path.sep + shapeName
+    
+def getNullShapeShape(scale = 1.0):
+    """obtains a shape intended ad a placeholder in case null shape was produced by an operation"""
+    
+    #read shape from file, if not done this before
+    global _nullShapeShape
+    if not _nullShapeShape:
+        _nullShapeShape = Part.Shape()
+        f = open(getShapePath("empty-shape.brep"))
+        _nullShapeShape.importBrep(f)
+        f.close()
+    
+    #scale the shape
+    ret = _nullShapeShape
+    if scale != 1.0:
+        ret = _nullShapeShape.copy()
+        ret.scale(scale)
+        
+    return ret