6b09857f55 base58: Re-name crate to base58ck (Tobin C. Harding)
Pull request description:
The current name `base58check` is taken, as is `base58`. Use `base58ck` instead.
Add a brief section to the readme about the crate naming.
ACKs for top commit:
apoelstra:
ACK 6b09857f55
sanket1729:
ACK 6b09857f55
Tree-SHA512: 86ee08105906a6f3403dc2602e827b0d46226798ecdedb420ad3ac4b657d6a00e25eabcdfbdb9f8e89bdc3a38e608189f1e073e65593f89a2ad853e8ff027f69