Manipulator: split alpha out of color property

Gives more convenient access from Python: `mathutils.Color`

Also correct some copy-paste error w/ property subtypes.

release/scripts/templates_py/manipulator_operator.py

@@ -130,8 +130,12 @@ class SelectSideOfPlaneManipulatorGroup(ManipulatorGroup):
 
         mpr.use_draw_value = True
 
-        mpr.color = 0.8, 0.8, 0.8, 0.5
-        mpr.color_highlight = 1.0, 1.0, 1.0, 1.0
+        mpr.color = 0.8, 0.8, 0.8
+        mpr.alpha = 0.5
+
+        mpr.color_highlight = 1.0, 1.0, 1.0
+        mpr.alpha_highlight = 1.0
+
         mpr.scale_basis = 0.2
 
         self.widget_grab = mpr
@@ -162,8 +166,11 @@ class SelectSideOfPlaneManipulatorGroup(ManipulatorGroup):
 
         mpr.use_draw_value = True
 
-        mpr.color = 0.8, 0.8, 0.8, 0.5
+        mpr.color = 0.8, 0.8, 0.8
+        mpr.alpha = 0.5
+
         mpr.color_highlight = 1.0, 1.0, 1.0, 1.0
+        mpr.alpha_highlight = 1.0
 
         self.widget_dial = mpr
 

release/scripts/templates_py/manipulator_operator_target.py

@@ -32,8 +32,11 @@ class MyCameraWidgetGroup(ManipulatorGroup):
         mpr.matrix_basis = ob.matrix_world.normalized()
         mpr.line_width = 3
 
-        mpr.color = 0.8, 0.8, 0.8, 0.5
-        mpr.color_highlight = 1.0, 1.0, 1.0, 1.0
+        mpr.color = 0.8, 0.8, 0.8
+        mpr.alpha = 0.5
+
+        mpr.color_highlight = 1.0, 1.0, 1.0
+        mpr.alpha_highlight = 1.0
 
         self.roll_widget = mpr
 

release/scripts/templates_py/manipulator_simple.py

@@ -29,8 +29,11 @@ class MyLampWidgetGroup(ManipulatorGroup):
         mpr.matrix_basis = ob.matrix_world.normalized()
         mpr.draw_style = 'BOX'
 
-        mpr.color = 1, 0.5, 0, 0.5
-        mpr.color_highlight = 1, 0.5, 1, 0.5
+        mpr.color = 1.0, 0.5, 0.0
+        mpr.alpha = 0.5
+
+        mpr.color_highlight = 1.0, 0.5, 1.0
+        mpr.alpha_highlight = 0.5
 
         self.energy_widget = mpr