Sculpt: Enable accumulate in scrape brush

This fixes some artifacts when working on curved surfaces. Previous
behavior was with accumulate on, so that is now the default.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D5826

source/blender/blenkernel/intern/brush.c

@@ -912,6 +912,7 @@ void BKE_brush_sculpt_reset(Brush *br)
     case SCULPT_TOOL_SCRAPE:
       br->alpha = 1.0f;
       br->spacing = 7;
+      br->flag |= BRUSH_ACCUMULATE;
       break;
     case SCULPT_TOOL_ROTATE:
       br->alpha = 1.0;

source/blender/makesdna/DNA_brush_types.h

@@ -498,6 +498,7 @@ typedef enum eBrushUVSculptTool {
        SCULPT_TOOL_CLAY, \
        SCULPT_TOOL_CLAY_STRIPS, \
        SCULPT_TOOL_ROTATE, \
+       SCULPT_TOOL_SCRAPE, \
        SCULPT_TOOL_FLATTEN)
 
 #define SCULPT_TOOL_HAS_NORMAL_WEIGHT(t) ELEM(t, SCULPT_TOOL_GRAB, SCULPT_TOOL_SNAKE_HOOK)