Show the current time, after a successful compile/send

When working on multiple projects, I often compile when I don't need to.
Many IDE's show either or both of the following:
1) Time of completed compile.
2) Counter or indicator of textual changes after compile/save.

Both of these enhance the user experience, and speed up productivity.

No files, tests, or entry points are named. Start by tracing the Arduino IDE flow that reports successful compile or send operations, then determine how completion time can be shown; done means the current time is visible after a successful operation.

Written by the indexing model from the issue text.