upgrd library : upgrade support for nxxm powered apps

nxxm is a modern dependency managers that goes beyond dependency management but also performs upgrade.

This is the upgrd library, with the ecosystem that nxxm is providing the goal is to make it a complete toolkit to perform software upgrade.

Features

• Relies on GitHub releases : once you tag and validate the release the apps starts downloading by your end user.
• Provides a simple to one-liner API for the usual scenarii.

  upgrd::manager up{
    "nxxm",
    "example-upgrd-app",
    "v0.0.1",
    argc,
    argv,
    std::cout
  };

  up.propose_upgrade_when_needed();

This will add the following command line switches to your app :

• --dont-upgrade : never perform the up-to-date check
• --force-upgrade : force program upgrade (always check)
• --auto-upgrade : check normally (once a day) but always do the upgrade without asking user.