title: TypeScriptCompile build action doesn't seem to do anything
body: <p>When I add a new TypeScript file to my solution, the system nicely gives me a (prefilled) .ts file with the .js file just below.  This configuration makes me think that the conversion from TypeScript to JavaScript is automatic.  This assumption is strengthened by the fact that the .ts file has a Build Action 'TypeScriptCompile'.  However, regardless of what I do (save a changed ts, compile the project ...), nothing really happens.</p>
  
  <p>I know I can add prebuild steps to the project but I would really like the TypeScriptCompile build action to automatically kick in so that I just need to save the file for the .js file to be regenerated.  What do I need to do to make 'TypeScriptCompile' from working as expected/desired ?</p>