Split npm start into an init and watch script

This is to better support riot-web's build process without losing the functionality supplied by `npm start`. The watch script no longer performs an initial build and thus `start:init` has been created for this purpose.

package.json

@@ -38,10 +38,12 @@
     "reskindex:watch": "node scripts/reskindex.js -h header -w",
     "i18n": "matrix-gen-i18n",
     "prunei18n": "matrix-prune-i18n",
-    "build": "npm run reskindex && babel src -d lib --source-maps --copy-files",
-    "build:watch": "babel src -w -d lib --source-maps --copy-files",
+    "build": "npm run reskindex && npm run start:init",
+    "build:watch": "babel src -w --skip-initial-build -d lib --source-maps --copy-files",
     "emoji-data-strip": "node scripts/emoji-data-strip.js",
-    "start": "parallelshell \"npm run build:watch\" \"npm run reskindex:watch\"",
+    "start": "npm run start:init && npm run start:all",
+    "start:all": "concurrently --kill-others-on-fail --prefix \"{time} [{name}]\" -n build,reskindex \"npm run build:watch\" \"npm run reskindex:watch\"",
+    "start:init": "babel src -d lib --source-maps --copy-files",
     "lint": "eslint src/",
     "lintall": "eslint src/ test/",
     "lintwithexclusions": "eslint --max-warnings 20 --ignore-path .eslintignore.errorfiles src test",
@@ -111,6 +113,7 @@
     "babel-preset-es2017": "^6.14.0",
     "babel-preset-react": "^6.11.1",
     "chokidar": "^1.6.1",
+    "concurrently": "^4.0.1",
     "eslint": "^3.13.1",
     "eslint-config-google": "^0.7.1",
     "eslint-plugin-babel": "^4.0.1",
@@ -133,7 +136,6 @@
     "matrix-mock-request": "^1.2.1",
     "matrix-react-test-utils": "^0.1.1",
     "mocha": "^5.0.5",
-    "parallelshell": "3.0.1",
     "react-addons-test-utils": "^15.4.0",
     "require-json": "0.0.1",
     "rimraf": "^2.4.3",