Rdwv

Added ability to get fiat price in most currencies

Now `rate()` method accepts optional currency argument to get it in currency other than USD.

New method: `list_fiat()` to get list of all supported fiat currencies.

Add `btc.rate()` method to get USD price of bitcoin

Use requests.Session for better performance

This is a small bugfix to fix pip description rendering.

Lightning network support is now in rdwv as defined by [rdwvcc/rdwv51](https://github.com/rdwvcc/rdwv/pull/51)

This adds in new LN class and related methods.

Also, now it is not needed to fill in all values, some defaults are used:

text
rpc_user="electrum"
rpc_pass="electrumz"
rpc_url="http://localhost:5000" for bitcoin daemon and "http://localhost:5001" for lightning daemon.


When xpub is not provided, a warning is created.

- Add type hints everywhere
- Code is checked with mypy and pylint
- Docs now available(check readme)
- Automatic deployment via circleci

And many more...