Transmission 4.1.4 fixes macOS RCE and download bugs

Transmission 4.1.4 is out with a fix for a potential remote code execution flaw in the macOS client, which requires local write access to preferences, plus a fix for a 4.1.0 regression that mishandled torrents with zero-byte files. The update also resolves rare webseed download failures, per-torrent speed limits and a shutdown hang.

• Potential macOS RCE fixed, but exploitation needs local write access to preferences
• 4.1.0 regression that lost progress on zero-byte-file torrents resolved
• Per-torrent speed-limit overrides now work for uploads and downloads
• Minimum macOS raised to 12; Qt and zlib updated in Windows builds