nfcgate/nfcgate: v2.0

2.0 version of NFCGate, with significant rewrites by @kleest and @roussosalex. Changes include:

• New interface: The interface got a facelift
• Replay Mode: Record a relayed NFC transaction, then replay one side of it later to fool a reader or card.
• Capture Mode: Capture NFC traffic generated by other apps, then analyze or replay it later. (Note: XPosed will make SafetyNet checks fail, so most payment apps will probably not work with XPosed installed. We cannot do anything about this.)
• PCAP Import/Export: Export recorded traffic as .pcapng files, and import it again for replays
• Modified relay / replay: Modify data on the fly during replay / relay. This functionality is enabled in the NFCGate server, check that repository for details.

• New package name and internal data format - you will likely loose existing data when updating
• New server version with updated protocol - update existing installs of the NFCGate server to stay compatible
• Reduced complexity of the codebase
• Remove dead code