ENH: Expose tip_resolution in pyvista.Arrow (pyvista#624)

Add omitted tip_resolution parameter to pyvista.Arrow.
Fixes pyvista#623

pyvista/utilities/geometric_objects.py

@@ -178,7 +178,8 @@ def CylinderStructured(radius=0.5, height=1.0,
 
 
 def Arrow(start=(0.,0.,0.), direction=(1.,0.,0.), tip_length=0.25,
-          tip_radius=0.1, shaft_radius=0.05, shaft_resolution=20):
+          tip_radius=0.1, tip_resolution=20, shaft_radius=0.05,
+          shaft_resolution=20):
     """Create a vtk Arrow.
 
     Parameters
@@ -195,11 +196,14 @@ def Arrow(start=(0.,0.,0.), direction=(1.,0.,0.), tip_length=0.25,
     tip_radius : float, optional
         Radius of the tip.
 
+    tip_resolution : int, optional
+        Number of faces around the tip.
+
     shaft_radius : float, optional
         Radius of the shaft.
 
     shaft_resolution : int, optional
-        Number of faces around the shaft
+        Number of faces around the shaft.
 
     Return
     ------
@@ -211,6 +215,7 @@ def Arrow(start=(0.,0.,0.), direction=(1.,0.,0.), tip_length=0.25,
     arrow = vtk.vtkArrowSource()
     arrow.SetTipLength(tip_length)
     arrow.SetTipRadius(tip_radius)
+    arrow.SetTipResolution(tip_resolution)
     arrow.SetShaftRadius(shaft_radius)
     arrow.SetShaftResolution(shaft_resolution)
     arrow.Update()