Net Ping, parameters, and preferences

I'm refining the changes to Net Ping that will allow users to change the parameters for pinging.

The preference framework that the Android SDK provides is pretty good for quick, generic app preferences. For a more polished user experience, the developer should put more work into the code.

Here is a screen shot of the preference screen in my development build.

Before I update to the Market, I have these things to wrap up:

1. Force the preference screen to get updated values when Reset is used.
2. Add a Go/Stop menu option on the main screen.  Now that the user can potentially start a very long-running ping operation, we need a way to stop it.
3. Present the numeric keyboard (instead of the alpha one) for these options.  The alpha keyboard appears by default now, and it's a little annoying to have to switch manually.
4. And, of course, testing.