v2.0.0 Major feature release

• [added] Add strong crypto, complete rewrite of crypto system
• [added] Automatically claim addresses based on interface addresses (disable with --no-auto-claim)
• [added] Allow to give --ip instead of ifup cmd
• [added] Automatically set optimal MTU on interface
• [added] Warning for disabled or loose rp_filter setting
• [added] Add --fix-rp-filter to fix rp filter settings
• [added] Offer to migrate old configs
• [changed] Complete change of network protocol
• [changed] Negotiate crypto method per peer, select best method
• [changed] Make encryption the default, no encryption must be stated explicitly
• [changed] Changed default device type to TUN
• [changed] Rename subnet to claim
• [changed] Set peer exchange interval to 5 minutes
• [changed] Periodically send claims with peer list
• [changed] Changed Rust version to 1.47.0
• [removed] Remove network-id parameter
• [removed] Remove port config option in favor of --listen