Tidemark 0.10.3

Fixed

• Update detection no longer depends on GitHub's API, whose anonymous rate limit shared hosts often exhaust. The newest version is read from github.com's release redirect; the API is only used for release notes. This could leave the update dot and the Updates page empty on shared hosting.
• Installed copies re-check every 6 hours while an administrator is using the app (they used to wait 24), so a new release shows its dot the same day.