Automatically find the name of the core bin file, instead of hardcoding #109

The Annoyance

Every time I create a new minicli app, I need to edit every mention of minicli to whatever the binary is.

If I want to rename the bin file, I have to edit every single mention of it in the app.

The Solution

1. Add a public readonly string $me to App so now you can call $app->me to get the filename.
2. Add a protected function findBinFileName(): string that will automagically find the filename.
3. Call this from within the App::__construct().

This way, the end-developer can easily do things like echo "{$app->me} commad";. You can't embed method calls into strings like that.

And the developer will never need to automate anything.