* display chain/network in header if not mainnet
* indicate active chain/network in startup log
* specify which chain/network "fun" items apply to and only show them for that chain
* don't display exchange rates for testnet/regtest
* use block interval of 150 for regtest halving
* regtest hacks: since getblockchaininfo.blocks=0 on a default regtest node despite the genesis block existing, hack in a couple of places in order to display the genesis block
* fix /peers page to not throw error with no connections
- footer: full-width to match header; remove bottom border
- extraneous padding removed from some tx lists
- fix some card-body wrapping issues for paginations at bottom
- table responsiveness improvements
- add some shadows for visual depth
- hide radial progress bars on small screens since they're not working properly
- text-wrapping improvement for addresses in tx io details
- add back previous/next block hashes to top summary table (and remove back/forward buttons recently added to header)
- make better use of horizontal space on large screens by splitting the top summary table when possible
- better semantic grouping of transactions
- button-links for previous/next blocks instead of showing the hashes in the table
- don't show block-hash or height in the summary table (since it's in the H1 title already)
- add "age" description for the age below the timestamp for clarity
- include "Total Fees" and "Average Fee" in the summary table
- include "Miner" entry even if unidentified, for consistency
- Some reorganization and renaming
- Ensure that blocks include their coinbase tx so we can query it to guess miner identity
- Use open-source miner-identification list to guess