This is a somewhat-obvious oversight in the capabilities of
rust-lightning, though not a particularly interesting one until we
start relying on node_features (eg for variable-length-onions and
Base AMP).
Sadly its not fully automated as we don't really want to store the
list of available addresses from the user. However, with a simple
call to ChannelManager::broadcast_node_announcement and a sensible
peer_handler, the announcement is made.
This makes Readable symmetric with Writeable and makes sense -
something which is Readable should be Readable for any stream which
implements std::io::Read, not only for a stream type it decides on.
This solves some lifetime-compatibility issues in trying to read()
from a LengthLimitingReader in arbitrary Readable impls.
As noted in the docs, Events don't round-trip fully, but round-trip
in a way that is useful for ChannelManagers, specifically some events
don't make sense anymore after a restart.
* Fixed a number of grammar issues
* Clarified the docs for users who are intimately farmiliar with
arbitrary lines of text copied from the BOLTs
* Added a bit more text so that things are easier to read and less
disjoint.
* Clarified exactly how the witness stack should look since I had
to go dig for it.
