Move exec and events components to util module

The exec and events components are common components that
are used by both runtime and registry. It makes sense to
move them into the util package.

This also adds some docs to the registry module

packages/node_modules/@node-red/registry/lib/util.js

@@ -14,9 +14,8 @@
  * limitations under the License.
  **/
 
-var path = require("path");
-var i18n = require("@node-red/util").i18n;
-var registry;
+const path = require("path");
+const {events,i18n,log} = require("@node-red/util");
 var runtime;
 
 function copyObjectProperties(src,dst,copyList,blockList) {
@@ -40,7 +39,7 @@ function copyObjectProperties(src,dst,copyList,blockList) {
     }
 }
 function requireModule(name) {
-    var moduleInfo = registry.getModuleInfo(name);
+    var moduleInfo = require("./index").getModuleInfo(name);
     if (moduleInfo && moduleInfo.path) {
         var relPath = path.relative(__dirname, moduleInfo.path);
         return require(relPath);
@@ -56,14 +55,14 @@ function createNodeApi(node) {
         nodes: {},
         log: {},
         settings: {},
-        events: runtime.events,
+        events: events,
         hooks: runtime.hooks,
         util: runtime.util,
         version: runtime.version,
         require: requireModule,
         comms: {
             publish: function(topic,data,retain) {
-                runtime.events.emit("comms",{
+                events.emit("comms",{
                     topic: topic,
                     data: data,
                     retain: retain
@@ -83,7 +82,7 @@ function createNodeApi(node) {
     red.nodes.registerType = function(type,constructor,opts) {
         runtime.nodes.registerType(node.id,type,constructor,opts);
     }
-    copyObjectProperties(runtime.log,red.log,null,["init"]);
+    copyObjectProperties(log,red.log,null,["init"]);
     copyObjectProperties(runtime.settings,red.settings,null,["init","load","reset"]);
     if (runtime.adminApi) {
         red.auth = runtime.adminApi.auth;
@@ -108,7 +107,6 @@ function createNodeApi(node) {
 module.exports = {
     init: function(_runtime) {
         runtime = _runtime;
-        registry = require("@node-red/registry/lib");
     },
     createNodeApi: createNodeApi
 }