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/util/lib/log.js

@@ -1,4 +1,4 @@
-/**
+/*!
  * Copyright JS Foundation and other contributors, http://js.foundation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -12,7 +12,6 @@
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
- * @ignore
  **/
 
 /**
@@ -91,7 +90,7 @@ var consoleLogger = function(msg) {
             } catch(e){
                 message = 'Exception trying to log: '+util.inspect(message);
             }
-            
+
             util.log("["+levelNames[msg.level]+"] "+(msg.type?"["+msg.type+":"+(msg.name||msg.id)+"] ":"")+message);
         }
     }