add mtb:scale, mtb:scale:uphill, mtb:scale:imba (closes #2244)

data/presets/fields/mtb/scale.json

@@ -0,0 +1,17 @@
+{
+    "key": "mtb:scale",
+    "type": "combo",
+    "label": "Mountain Biking Difficulty",
+    "placeholder": "0, 1, 2, 3...",
+    "strings": {
+        "options": {
+            "0": "0: Solid gravel/packed earth, no obstacles, wide curves",
+            "1": "1: Some loose surface, small obstacles, wide curves",
+            "2": "2: Much loose surface, large obstacles, easy hairpins",
+            "3": "3: Slippery surface, large obstacles, tight hairpins",
+            "4": "4: Loose surface or boulders, dangerous hairpins",
+            "5": "5: Maximum difficulty, boulder fields, landslides",
+            "6": "6: Not rideable except by the very best mountain bikers"
+        }
+    }
+}

data/presets/fields/mtb/scale/imba.json

@@ -0,0 +1,15 @@
+{
+    "key": "mtb:scale:imba",
+    "type": "combo",
+    "label": "IMBA Trail Difficulty",
+    "placeholder": "Easy, Medium, Difficult...",
+    "strings": {
+        "options": {
+            "0": "Easiest (white circle)",
+            "1": "Easy (green circle)",
+            "2": "Medium (blue square)",
+            "3": "Difficult (black diamond)",
+            "4": "Extremely Difficult (double black diamond)"
+        }
+    }
+}

data/presets/fields/mtb/scale/uphill.json

@@ -0,0 +1,16 @@
+{
+    "key": "mtb:scale:uphill",
+    "type": "combo",
+    "label": "Mountain Biking Uphill Difficulty",
+    "placeholder": "0, 1, 2, 3...",
+    "strings": {
+        "options": {
+            "0": "0: Avg. incline <10%, gravel/packed earth, no obstacles",
+            "1": "1: Avg. incline <15%, gravel/packed earth, few small objects",
+            "2": "2: Avg. incline <20%, stable surface, fistsize rocks/roots",
+            "3": "3: Avg. incline <25%, variable surface, fistsize rocks/branches",
+            "4": "4: Avg. incline <30%, poor condition, big rocks/branches",
+            "5": "5: Very steep, bike generally needs to be pushed or carried"
+        }
+    }
+}

data/presets/fields/sac_scale.json

@@ -1,7 +1,7 @@
 {
     "key": "sac_scale",
     "type": "combo",
-    "label": "Path Difficulty",
+    "label": "Hiking Difficulty",
     "placeholder": "Mountain Hiking, Alpine Hiking...",
     "strings": {
         "options": {

data/presets/fields/tracktype.json

@@ -1,7 +1,7 @@
 {
     "key": "tracktype",
     "type": "combo",
-    "label": "Type",
+    "label": "Track Type",
     "placeholder": "Solid, Mostly Solid, Soft...",
     "strings": {
         "options": {