Block Height Tracker

[maaatttt]

Request to explore additional commands for TARS bot in Ubiq Discord in regards to block height e.g;

• remaining blocks / estimated time remaining until mining reward reductions
• remaining blocks / estimated time remaining for Escher token airdrop claims
• remaining blocks / estimated time remaining for UIP votes
• remaining blocks / estimated time remaining to upgrade clients in regards to hard forks

[jyap808]

Added to Dikembe bot.

Thanks for the suggestion!