Show HN: An ultra-lightweight application auto-updater

Wanted an updater for a CLI utility so that a user could run "my-utility update" and have it self-updated.

Did not want to go through package managers, in order to have better distribution control.

Looked into Sparkle (and WinSparkle), Squirrel, GoUpdate, Google Omaha, and others.

All were very heavy, hard or impossible to use across multiple platforms, and carried their own UI component baggage. None came even close to meeting our needs. So we rolled our own.

`sxupdate` weighs in at about 100k, works on any platform and can be integrated with virtually any programming language. Using a bring-your-own-UI-component approach, it is extremely lean, platform-independent, applicable to either console or UI-based applications, and avoids duplication of and potential inconsistency between the application and the updater UIs.

Hope someone else can get some mileage out of it. We sure have.