Merge branch '2.1' of https://github.com/Ultimaker/Cura into 2.1

plugins/LegacyProfileReader/DictionaryOfDoom.json

@@ -50,7 +50,7 @@
         "skirt_minimal_length": "skirt_minimal_length",
         "brim_line_count": "brim_line_count",
         "raft_margin": "raft_margin",
-        "raft_airgap": "float(raft_airgap_all) - float(raft_airgap)",
+        "raft_airgap": "float(raft_airgap_all) + float(raft_airgap)",
         "layer_0_z_overlap": "raft_airgap",
         "raft_surface_layers": "raft_surface_layers",
         "raft_surface_thickness": "raft_surface_thickness",