* Use Markdown for Android build docs, fix typos
* Format and correct syntax errors/irregularities in existing Markdown documents
* Convert `txt`-based docs to Markdown, update macOS instructions
* Use GitHub conventions for README, fix typos, add link to `gon2n`
* Fix case sensitivity issues
1. Some nat router blocks the port if incoming traffic arrives before outcoming traffic being sent. Give edge ability to set proper TTL so that the registration packet is dropped before it arrives peer.
2. Support Symmetric NAT by predicting 15 more ports when sending registration packet
3. Purge pending mac also on P2P normal packet. This is actually more usual condition.
4. Add doc for new flag.
