Refactor coininfo versions structure

P2SH is part of the cryptocurrency, and not something standalone. IMHO it makes more sense to represent it that way. Also, some crypto-currencies have different version bytes for P2SH, which can't work with the previous format.

I changed the P2SH handling, as well as a few other small changes:

- Moved P2SH version into each cryptocurrency, rather than being represented as its own cryptocurrency
- Return P2SH version as a new `p2sh` key in the versions object
- Renamed TEST to BTC-TEST
- Added deprecation warning for TEST (now BTC-TEST), P2SH (now part of BTC) and TEST-P2SH (now part of BTC-TEST)
- Added LTC-TEST (wanted to add NMC-TEST too, but couldn't figure out the version bytes)