chore(project): build pre-packaged distros with Rollup

* enables tree-shaking
* simplifies build

rollup.config.js

@@ -0,0 +1,140 @@
+import uglify from 'rollup-plugin-uglify';
+import nodeResolve from 'rollup-plugin-node-resolve';
+import commonjs from 'rollup-plugin-commonjs';
+import json from 'rollup-plugin-json';
+import license from 'rollup-plugin-license';
+import replace from 'rollup-plugin-replace';
+
+import {
+  readFileSync
+} from 'fs';
+
+import pkg from './package.json';
+
+const outputDir = 'dist';
+
+const distros = [
+  {
+    input: 'Viewer',
+    output: 'bpmn-viewer'
+  },
+  {
+    input: 'NavigatedViewer',
+    output: 'bpmn-navigated-viewer'
+  },
+  {
+    input: 'Modeler',
+    output: 'bpmn-modeler'
+  }
+];
+
+const configs = distros.reduce(function(configs, distro) {
+  const {
+    input,
+    output
+  } = distro;
+
+  return [
+    ...configs,
+    {
+      input: `./lib/${input}.js`,
+      output: {
+        name: 'BpmnJS',
+        file: `${outputDir}/${output}.development.js`,
+        format: 'umd'
+      },
+      plugins: pgl([
+        banner(output)
+      ])
+    },
+    {
+      input: `./lib/${input}.js`,
+      output: {
+        name: 'BpmnJS',
+        file: `${outputDir}/${output}.production.min.js`,
+        format: 'umd'
+      },
+      plugins: pgl([
+        banner(output, true),
+        uglify({
+          output: {
+            comments: /license|@preserve/
+          }
+        })
+      ])
+    }
+  ];
+}, []);
+
+export default configs;
+
+
+// helpers //////////////////////
+
+function banner(bundleName, minified) {
+
+  const bannerName = (
+    minified
+      ? 'banner-min'
+      : 'banner'
+  );
+
+  const bannerTemplate = readFileSync(`${__dirname}/resources/${bannerName}.txt`, 'utf8');
+
+  const banner = processTemplate(bannerTemplate, {
+    version: pkg.version,
+    date: today(),
+    name: bundleName
+  });
+
+  return license({
+    banner
+  });
+}
+
+function pgl(plugins=[]) {
+  return [
+    replace({
+      'process.env.NODE_ENV': JSON.stringify('production')
+    }),
+    nodeResolve({
+      module: true,
+      main: true,
+      browser: true
+    }),
+    commonjs(),
+    json(),
+    ...plugins
+  ];
+}
+
+function pad(n) {
+  if (n < 10) {
+    return '0' + n;
+  } else {
+    return n;
+  }
+}
+
+function today() {
+  const d = new Date();
+
+  return [
+    d.getFullYear(),
+    pad(d.getMonth() + 1),
+    pad(d.getDay())
+  ].join('-');
+}
+
+function processTemplate(str, args) {
+  return str.replace(/\{\{\s*([^\s]+)\s*\}\}/g, function(_, n) {
+
+    var replacement = args[n];
+
+    if (!replacement) {
+      throw new Error('unknown template {{ ' + n + '}}');
+    }
+
+    return replacement;
+  });
+}