cleanup raft speeds

raft base speed is only 15mm/s to avoid extreme flows. The raft surface speed equals the top/bottom speed, so the raft surface has a flow equal to the top/bottom flow. The raft interface is again the average of the surface and the base. PP-243

resources/definitions/ultimaker.def.json

@@ -239,15 +239,27 @@
         "gradual_support_infill_step_height": {
             "value": "4*layer_height"
         },
+        "raft_base_speed": {
+            "value": "raft_speed"
+        },
         "raft_base_thickness": {
             "value": "min(machine_nozzle_size * 0.75, 0.3)"
         },
         "raft_interface_line_width": {
             "value": "(raft_base_line_width + raft_surface_line_width) / 2"
         },
+        "raft_interface_speed": {
+            "value": "(raft_surface_speed + raft_base_speed) /2"
+        },
         "raft_interface_thickness": {
             "value": "(raft_base_thickness + raft_surface_thickness) / 2"
         },
+        "raft_speed": {
+            "value": 15
+        },
+        "raft_surface_speed": {
+            "value": "speed_topbottom"
+        },
         "support_interface_height": {
             "value": "2*layer_height"
         },

resources/definitions/ultimaker_s3.def.json

@@ -101,9 +101,6 @@
         "optimize_wall_printing_order": { "value": "True" },
         "prime_tower_enable": { "value": "True" },
         "raft_airgap": { "value": "0" },
-        "raft_base_speed": { "value": "20" },
-        "raft_interface_speed": { "value": "20" },
-        "raft_speed": { "value": "25" },
         "retraction_amount": { "value": "6.5" },
         "retraction_hop": { "value": "2" },
         "retraction_hop_enabled": { "value": "extruders_enabled_count > 1"  },

resources/definitions/ultimaker_s5.def.json

@@ -102,9 +102,6 @@
         "multiple_mesh_overlap": { "value": "0" },
         "prime_tower_enable": { "value": "True" },
         "raft_airgap": { "value": "0" },
-        "raft_base_speed": { "value": "20" },
-        "raft_interface_speed": { "value": "20" },
-        "raft_speed": { "value": "25" },
         "retraction_amount": { "value": "6.5" },
         "retraction_combing": { "value": "'no_outer_surfaces'"},
         "retraction_hop": { "value": "2" },