Use prepare instead of build as script

The prepare script runs before publishing a package, after installation
of a package from source, and when running npm install without
arguments in the repository.  These are the times where a build of the
web interface files are required to make the web interface work and
removes a manual step from using the package(s). The "build" script on
the other hand is never automatically invoked by npm.

plugins/global_chat/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/clusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {

plugins/inventory_sync/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/factorioClusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {

plugins/player_auth/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/clusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {

plugins/research_sync/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/clusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {

plugins/statistics_exporter/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/clusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {

plugins/subspace_storage/package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "repository": "clusterio/clusterio",
   "scripts": {
-    "build": "webpack-cli --env production",
+    "prepare": "webpack-cli --env production",
     "test": "echo \"Error: run tests from root\" && exit 1"
   },
   "bugs": {