Add SLP coin type for Bitcoin Cash

[EchterAgo]

Electron Cash SLP defaults to the 245 (SLP) coin type for its derivation paths:

https://github.com/simpleledger/Electron-Cash-SLP/blob/master/lib/keystore.py#L803

This causes newer versions of app-bitcoin to warn about an unusual derivation path. The 245 derivation path should be considered normal for Bitcoin Cash.