Add concept of global config, and use that to control setMaxListeners

fixes #81

README.md

@@ -128,6 +128,17 @@ Tests run *perfectly*, ship it to the enterprise!
 Once you have the watcher running, you can force restart all tasks by entering `rs`.
 If you want to only force a single task, type the name of the key from the watch config (for example `rs test`).
 
+### Global Config
+
+#### `setMaxListeners`
+If too many listeners are added to an event emitter, [`node.js` will send a warning (rightfully so) about potential memory leaks](https://nodejs.org/docs/latest/api/events.html#events_emitter_setmaxlisteners_n).
+The default maximum is 10. If you need more than that, you can add a top level global config to your package.json
+```json
+"watchGlobalConfig": {
+    "setMaxListeners": true
+}
+```
+And max listeners will be set on the relevant processes to the minimum needed to avoid the warning.
 ### Options
 
 #### `patterns`

watch-package.js

@@ -61,12 +61,17 @@ module.exports = function watchPackage(_pkgDir, exit, taskName) {
     }
     startScript(taskName, pkg, processes);
   } else {
-
+    // We only look for the global watch config here, since it is otherwise not relevant
+    var setMaxListeners = null;
+    if (typeof pkg.watchGlobalConfig === 'object') {
+      setMaxListeners = pkg.watchGlobalConfig.setMaxListeners
+    }
+    var scriptsCount = Object.keys(pkg.watch).length;
   Object.keys(pkg.watch).forEach(function (script) {
     if (!pkg.scripts[script]) {
       die('No such script "' + script + '"', 2)
     }
-    startScript(script, pkg, processes);
+    startScript(script, pkg, processes, setMaxListeners, scriptsCount + 1);
   })
   }
 
@@ -94,7 +99,7 @@ function prefixer(prefix) {
   })
 }
 
-function startScript(script, pkg, processes) {
+function startScript(script, pkg, processes, setMaxListeners,  scriptsCount) {
   var exec = [npm, 'run', '-s', script].join(' ')
     var patterns = null
     var extensions = null
@@ -148,7 +153,12 @@ function startScript(script, pkg, processes) {
     if (delay) { args = args.concat(['--delay', delay + 'ms']) }
     if (verbose) { args = args.concat(['-V']) }
     if (silent) { args = args.concat(['-q']) }
-	  if (runOnChangeOnly) { args = args.concat(['--on-change-only']) }
+    if (runOnChangeOnly) { args = args.concat(['--on-change-only']) }
+    if (setMaxListeners){
+      process.setMaxListeners(scriptsCount)
+      stdin.stdout.setMaxListeners(scriptsCount)
+      stdin.stderr.setMaxListeners(scriptsCount)
+    }
     args = args.concat(['--exec', exec])
 
     var proc = processes[script] = spawn(nodemon, args, {