Add event to create modification update

[LucienMP]

See original repo this was forked to for feature request ; Original Repo Issue

How to compile the minimized example;

1. clone this repo
2. move to drawio/etc/build
3. from command line type; ant
4. Wait for compile to finish, you should see an app.min.js
5. Change access permissions if on linux to 666 in src/main/webapp/js/app.min.js

How to test;

• open the drawio/example/index.html from apache
• open browser dev console and see various event messages from message handler

How to load DEBUG DrawIO non-minimized JS:

1. Add URL to the https://.../drawio.git/src/main/webapp/index.html?dev=1&....other-param....
2. Edit drawio.git/src/main/webapp/index.html : var mxDevUrl / drawDevUrl to point to localhost/drawio.git
3. Edit drawio.git/src/main/webapp/index.html : mxscript( mxBasePAth + 'mxClient.js'); to mxscript( mxBasePAth + '/javascript/mxClient.js');
4. git clone https://github.com/jgraph/mxgraph into drawio.git/src/main/

Tools;
Linux; install "apache ant" and "java" compiler, follow compile flow
Windows;

1. Download Apache Ant Windows ZIP; https://ant.apache.org/bindownload.cgi
2. Unzip to some folder like C:\ANT
3. Download Oracle JDK ZIP ; https://www.oracle.com/java/technologies/javase-jdk15-downloads.html#license-lightbox
4. Unzip to some folder like C:\JDK
5. Open a command shell and ...
   5.1. add JDK to your path "SET PATH=%PATH%;C:\JDK\bin"
   5.2 Move to drawio/etc/build
   5.3 Then compile using "C:\ANT\bin\ant.bat"

NOTE:

The JSON actions can be seen in the below snippet.

EditorUi.js contains L11084:

     ...
     else if ( data.action == 'dialog' )
     ...

The autosave action can be seen in the below snippet, sometimes it triggers on EVERY change.
However not always.

EditorUi.js contains L11660:

     ...
     if( autosave && changeListener == null )
     {
         ...
         if( data != lastData && !ignoreChange )
         {
           ...
           parent.postMessage( 'autosave', ... );
           ...