Sculpt: Repeat last stroke for sculpt

Add support for repeating strokes to sculpt mode:
 * `paint_brush_stroke_add_step` no longer deletes the stroke RNA
   data if the paint operator has flag `OPTYPE_REGISTER` set.
 * Added a new method `WM_operator_repeat_clone` that repeats
   with a cloned operator (it just calls `wm_operator_invoke`).
 * Added a "repeat last relative" operator that executes the last
   stroke at the current brush location using a tangent frame derived
   from the surface normal and the camera. It's shortcut is
   `Shift-Alt-R`.

@@ -5630,6 +5630,40 @@ bool SCULPT_handles_colors_report(SculptSession *ss, ReportList *reports)
   return false;
 }
 
+void SCULPT_create_repeat_frame(Object *ob, float mat[3][3], float viewinv[4][4], float normal[3])

@@ -5632,1 +5632,4 @@
 
+void SCULPT_create_repeat_frame(Object *ob, float mat[3][3], float viewinv[4][4], float normal[3])
+{
+  float viewTan[3] = {1.0f, 0.0f, 0.0f};

@@ -5633,0 +5634,4 @@
+{
+  float viewTan[3] = {1.0f, 0.0f, 0.0f};
+
+  invert_m4_m4(ob->world_to_object, ob->object_to_world);

@@ -5954,3 +5992,3 @@
 
   /* Flags (sculpt does own undo? (ton)). */
-  ot->flag = OPTYPE_BLOCKING;
+  ot->flag = OPTYPE_BLOCKING | OPTYPE_REGISTER;

@@ -5959,3 +5997,4 @@
 
   paint_stroke_operator_properties(ot);
 
+  RNA_def_float_array(ot->srna, "repeat_tangent_frame", 9, 0, -1, 1, "", "", 0, 0);

@@ -1362,0 +1387,4 @@
+    return false;
+  }
+  wmWindowManager *wm = CTX_wm_manager(C);
+  return !BLI_listbase_is_empty(&wm->operators);

@@ -1362,0 +1448,4 @@
+  RNA_END;
+
+  WM_operator_free_all_after(wm, lastop);
+  WM_operator_repeat_clone(C, lastop);

@@ -1362,0 +1450,4 @@
+  WM_operator_free_all_after(wm, lastop);
+  WM_operator_repeat_clone(C, lastop);
+
+  return OPERATOR_CANCELLED;

@@ -746,3 +746,3 @@
 int WM_operator_repeat(bContext *C, wmOperator *op);
 int WM_operator_repeat_last(bContext *C, wmOperator *op);
-/**
+int WM_operator_repeat_clone(bContext *C, wmOperator *op);

@@ -748,1 +748,3 @@
-/**
+int WM_operator_repeat_clone(bContext *C, wmOperator *op);
+
+    /**

@@ -1649,6 +1653,7 @@ int paint_stroke_exec(bContext *C, wmOperator *op, PaintStroke *stroke)
 
   if (stroke->stroke_started) {
     RNA_BEGIN (op->ptr, itemptr, "stroke") {
+      stroke->ups->overlap_factor = RNA_float_get(&itemptr, "overlap_factor");

@@ -5633,0 +5641,4 @@
+  float3 view_tan = {1.0f, 0.0f, 0.0f};
+  bool success;
+
+  float4x4 world_to_object = invert(float4x4(ob->object_to_world), success);

@@ -5960,2 +6000,4 @@
   paint_stroke_operator_properties(ot);
 
+  PropertyRNA *prop = RNA_def_float_array(ot->srna, "repeat_tangent_frame", 9, 0, -1, 1, "", "", 0, 0);
+  RNA_def_property_flag(prop, PROP_SKIP_SAVE|PROP_HIDDEN);

@@ -3939,1 +3939,4 @@
 
+  prop = RNA_def_property(srna, "overlap_factor", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_flag(prop, PROP_IDPROPERTY);
+  RNA_def_property_ui_text(prop, "Factor used to attenuate strength from spacing.", "");