Add shepherd.js for later.

Note to self: Maybe do that work in a branch & merge it early? We'll 
need to branch off master though, and that could get messy :-/

Probably best just to finish up with the SVGOverlay stuff first.

package-lock.json

@@ -1034,6 +1034,11 @@
       "integrity": "sha512-mN2qeapQWdi2B9uddxTZ4nl80y46hbyKY5Wt9Yjih+QZFQLdaujEDK4qJky35WhyxMzHF3ZY41Lgjd2BPDuBhg==",
       "dev": true
     },
+    "element-matches": {
+      "version": "0.1.2",
+      "resolved": "https://registry.npmjs.org/element-matches/-/element-matches-0.1.2.tgz",
+      "integrity": "sha512-yWh1otcs3OKUWDvu/IxyI36ZI3WNaRZlI0uG/DK6fu0pap0VYZ0J5pEGTk1zakme+hT0OKHwhlHc0N5TJhY6yQ=="
+    },
     "emojis-list": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/emojis-list/-/emojis-list-2.1.0.tgz",
@@ -1755,12 +1760,27 @@
       "integrity": "sha1-soqmKIorn8ZRA1x3EfZathkDMaY=",
       "dev": true
     },
+    "lodash.defer": {
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/lodash.defer/-/lodash.defer-4.1.0.tgz",
+      "integrity": "sha1-6cFYqWHeGkbqJP2jRoW0zN01jz8="
+    },
     "lodash.get": {
       "version": "4.4.2",
       "resolved": "https://registry.npmjs.org/lodash.get/-/lodash.get-4.4.2.tgz",
       "integrity": "sha1-LRd/ZS+jHpObRDjVNBSZ36OCXpk=",
       "dev": true
     },
+    "lodash.iselement": {
+      "version": "4.1.1",
+      "resolved": "https://registry.npmjs.org/lodash.iselement/-/lodash.iselement-4.1.1.tgz",
+      "integrity": "sha1-9njU9vOpZPnsfxFfJUbz5KC6gso="
+    },
+    "lodash.isobjectlike": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/lodash.isobjectlike/-/lodash.isobjectlike-4.0.0.tgz",
+      "integrity": "sha1-dCxfxlrdJ5JNPSQZFoGqmheytg0="
+    },
     "lodash.memoize": {
       "version": "4.1.2",
       "resolved": "https://registry.npmjs.org/lodash.memoize/-/lodash.memoize-4.1.2.tgz",
@@ -1773,6 +1793,11 @@
       "integrity": "sha1-0CJTc662Uq3BvILklFM5qEJ1R3M=",
       "dev": true
     },
+    "lodash.zipobject": {
+      "version": "4.1.3",
+      "resolved": "https://registry.npmjs.org/lodash.zipobject/-/lodash.zipobject-4.1.3.tgz",
+      "integrity": "sha1-s5n1q6j/YqdG9peb8gshT5ZNvvg="
+    },
     "magic-string": {
       "version": "0.25.2",
       "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.25.2.tgz",
@@ -2107,6 +2132,11 @@
       "integrity": "sha1-5aSs0sEB/fPZpNB/DbxNtJ3SgXY=",
       "dev": true
     },
+    "popper.js": {
+      "version": "1.15.0",
+      "resolved": "https://registry.npmjs.org/popper.js/-/popper.js-1.15.0.tgz",
+      "integrity": "sha512-w010cY1oCUmI+9KwwlWki+r5jxKfTFDVoadl7MSrIujHU5MJ5OR6HTDj6Xo8aoR/QsA56x8jKjA59qGH4ELtrA=="
+    },
     "posix-character-classes": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/posix-character-classes/-/posix-character-classes-0.1.1.tgz",
@@ -3878,6 +3908,19 @@
         }
       }
     },
+    "shepherd.js": {
+      "version": "2.9.1",
+      "resolved": "https://registry.npmjs.org/shepherd.js/-/shepherd.js-2.9.1.tgz",
+      "integrity": "sha512-gHHPvDh2v2tSKMd5gcS7Kjmeji3pyqhYn7CHyyIe7o/B0CIXs8MgDt3wC/h72Gat5433/+GtxQwqSr8oDQOpGQ==",
+      "requires": {
+        "element-matches": "^0.1.2",
+        "lodash.defer": "^4.1.0",
+        "lodash.iselement": "^4.1.1",
+        "lodash.isobjectlike": "^4.0.0",
+        "lodash.zipobject": "^4.1.3",
+        "tippy.js": "^4.3.4"
+      }
+    },
     "simple-swizzle": {
       "version": "0.2.2",
       "resolved": "https://registry.npmjs.org/simple-swizzle/-/simple-swizzle-0.2.2.tgz",
@@ -4224,6 +4267,14 @@
       "integrity": "sha1-QFQRqOfmM5/mTbmiNN4R3DHgK9Q=",
       "dev": true
     },
+    "tippy.js": {
+      "version": "4.3.4",
+      "resolved": "https://registry.npmjs.org/tippy.js/-/tippy.js-4.3.4.tgz",
+      "integrity": "sha512-O2ukxHOJTLVYZ/TfHjNd8WgAWoefX9uk5QiWRdHfX2PR2lBpUU4BJQLl7U2Ykc8K7o16gTeHEElpuRfgD5b0aA==",
+      "requires": {
+        "popper.js": "^1.14.7"
+      }
+    },
     "to-object-path": {
       "version": "0.3.0",
       "resolved": "https://registry.npmjs.org/to-object-path/-/to-object-path-0.3.0.tgz",

package.json

@@ -27,6 +27,7 @@
 		"leaflet.markercluster": "^1.4.1",
 		"moment": "^2.24.0",
 		"nanomodal": "^5.1.1",
+		"shepherd.js": "^2.9.1",
 		"smartsettings": "^1.2.3",
 		"tabs": "^0.2.0",
 		"xml-writer": "^1.7.0"