Add Via field to route relations (re: #104)

data/fields/via.json

@@ -0,0 +1,6 @@
+{
+    "key": "via",
+    "type": "semiCombo",
+    "label": "Via",
+    "snake_case": false
+}

data/presets/type/route/bicycle.json

@@ -7,7 +7,8 @@
         "cycle_network",
         "network/type",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "ascent",

data/presets/type/route/hiking.json

@@ -7,7 +7,8 @@
         "network_foot",
         "network/type",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "ascent",

data/presets/type/route/horse.json

@@ -7,7 +7,8 @@
         "network_horse",
         "network/type",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "ascent",

data/presets/type/route/piste.json

@@ -6,7 +6,8 @@
         "ref_route",
         "operator",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "ascent",

data/presets/type/route/road.json

@@ -5,7 +5,8 @@
         "ref_route",
         "network_road",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "colour",

data/presets/type/route/train.json

@@ -6,7 +6,8 @@
         "operator",
         "network",
         "from",
-        "to"
+        "to",
+        "via"
     ],
     "moreFields": [
         "colour",