GPencil: New Hardeness mode for Opacity modifier

Add  new option to change the stroke hardeness. This option works at stroke level, not at point level.

Also replaced the "Both" name mode by "Stroke and Fill".

Differential Revision: https://developer.blender.org/D7195

release/scripts/startup/bl_ui/properties_data_modifier.py

@@ -1996,16 +1996,21 @@ class DATA_PT_gpencil_modifiers(ModifierButtonsPanel, Panel):
         split = layout.split()
 
         col = split.column()
-        col.prop(md, "normalize_opacity")
-        if md.normalize_opacity is True:
-            text="Strength"
-        else:
-            text="Opacity Factor"
-
-        col.prop(md, "factor", text=text)
         col.prop(md, "modify_color")
 
-        self.gpencil_masking(layout, ob, md, True, True)
+        if md.modify_color == 'HARDENESS':
+            col.prop(md, "hardeness")
+            show = False
+        else:
+            col.prop(md, "normalize_opacity")
+            if md.normalize_opacity is True:
+                text="Strength"
+            else:
+                text="Opacity Factor"
+
+            col.prop(md, "factor", text=text)
+            show = True
+        self.gpencil_masking(layout, ob, md, show, show)
 
     def GP_ARRAY(self, layout, ob, md):
         col = layout.column()