v0.4.2

Fixed

• mxctl --version now reports the correct version at runtime (was stuck at 0.3.0 since the rename)
• Consolidated duplicate get_headers() / get_raw_headers() code in system.py
• Moved delayed inline imports to module level in actions.py (subprocess, sys, get_gmail_accounts)
• Fixed ARCHITECTURE.md stale claim: "Six" → "Five" pragma:no cover guards