Add support for Filecoin

[riptl]

Description

Name: Filecoin
HD Derivation Scheme: tbd
Symbol: FIL
Documentation:

• Specification
• Lotus Node Docs
• Lotus Node Source
• Testnet Explorer

Blockers

• Wait for Filecoin to obtain SLIP-44 ID (slip-0044: add Filecoin satoshilabs/slips#841)
• Work out BIP-44 derivation paths
• Select key pair type (BLS or secp256k1)

Checklist

Finish check list here.

[hewigovens]

I think we can open a slipp44 pull request behalf of Filecoin team ？

[riptl]

@hewigovens Good idea. I think the Filecoin team has already started work on the SLIP44 issue though. I'll check with them.

[riptl]

Update: @jleni Has volunteered to get the SLIP44

[jleni]

Yes, here is the PR satoshilabs/slips#841

[prusnak]

Remember that All Testnets should use 1 as SLIP-44 value

[optout21]

Target is now mainnet (not test). @terorie , could you pls update description accordingly?