Various wallet features

[waynegeorge]

Improving grin wallet [High priority]

-Fixing some bugs and sub-optimal behavior, see sub-issues

Testing and fixing bugs in grin-wallet contract branch:

mimblewimble/grin-wallet#730
mimblewimble/grin-wallet#729

Python wallet tool for power users build on mimblewimble-py [Low priority]

• Generate grin vouchers
• Wallets with a BIP39 password
• brain wallets (with slightly better security)
• wallets based on custom non default word lists (to allow secret mnemonics).

[waynegeorge]

• PR pending for bottleneck bug fixes in config generation: Ready for review: Fix for many wallet config errors including solution for -h and -t wrongly setting the node path mimblewimble/grin-wallet#732
• grin-wallet not showing tor address when running grin-wallet listen, see this issue grin-wallet listen generates address without Mainnet or Testnet prefix OR shows pubkey mimblewimble/grin-wallet#740