fix bech32 prefix
bumped version
improve trie read RAM use, fix a few compiler warnings
open segwit window until Jan 2020
work around Windows ICU build issue
upped the soft fork thresh length to a week
open testnet soft forks window
clarifying segwit to be manually enabled
same for testnet
This contains significant rebase / merge / testing work by Naut
<lbrynaut@protonmail.com>, Anthony Fieroni <bvbfan@abv.bg> and Brannon
King <countprimes@gmail.com>.