[chirp_users] Updating CHIRP

[N4AOF]

A Check_For_Updates function would be nice to have, BUT it sounds like 
implementing it in a way that satisfies everyone would be tricky.

Ideally, the function would be configurable so that it could check for 
updates:
- Each time CHIRP starts
- Daily
- Weekly
- Only When The User Clicks a Button

Many programs have a setup option similar to this - I know both the video 
players that I use regularly give be options similar to this.

But the Check_For_Updates would also need to recognize that there are 
different kinds of updates.

I would think that if someone were running the Stable version, it should 
only check for updates of the Stable version.

If someone were running a Daily Build, perhaps it should notify them if 
there is a newer Daily Build (which would happen very often) AND if there is 
a Stable version newer than their Daily Build