Update to popper.js v2.x

package-lock.json

@@ -1157,6 +1157,12 @@
         "fastq": "^1.6.0"
       }
     },
+    "@popperjs/core": {
+      "version": "2.4.2",
+      "resolved": "https://registry.npmjs.org/@popperjs/core/-/core-2.4.2.tgz",
+      "integrity": "sha512-JlGTGRYHC2QK+DDbePyXdBdooxFq2+noLfWpRqJtkxcb/oYWzOF0kcbfvvbWrwevCC1l6hLUg1wHYT+ona5BWQ==",
+      "dev": true
+    },
     "@rollup/plugin-babel": {
       "version": "5.2.2",
       "resolved": "https://registry.npmjs.org/@rollup/plugin-babel/-/plugin-babel-5.2.2.tgz",
@@ -1204,6 +1210,16 @@
         "resolve": "^1.19.0"
       }
     },
+    "@rollup/plugin-replace": {
+      "version": "2.3.4",
+      "resolved": "https://registry.npmjs.org/@rollup/plugin-replace/-/plugin-replace-2.3.4.tgz",
+      "integrity": "sha512-waBhMzyAtjCL1GwZes2jaE9MjuQ/DQF2BatH3fRivUF3z0JBFrU0U6iBNC/4WR+2rLKhaAhPWDNPYp4mI6RqdQ==",
+      "dev": true,
+      "requires": {
+        "@rollup/pluginutils": "^3.1.0",
+        "magic-string": "^0.25.7"
+      }
+    },
     "@rollup/pluginutils": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/@rollup/pluginutils/-/pluginutils-3.1.0.tgz",
@@ -8228,12 +8244,6 @@
       "integrity": "sha512-Nc3IT5yHzflTfbjgqWcCPpo7DaKy4FnpB0l/zCAW0Tc7jxAiuqSxHasntB3D7887LSrA93kDJ9IXovxJYxyLCA==",
       "dev": true
     },
-    "popper.js": {
-      "version": "1.16.1",
-      "resolved": "https://registry.npmjs.org/popper.js/-/popper.js-1.16.1.tgz",
-      "integrity": "sha512-Wb4p1J4zyFTbM+u6WuO4XstYx4Ky9Cewe4DWrel7B0w6VVICvPwdOpotjzcf6eD8TsckVnIMNONQyPIUFOUbCQ==",
-      "dev": true
-    },
     "posix-character-classes": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/posix-character-classes/-/posix-character-classes-0.1.1.tgz",