Docs can always do with a bit of love.
Clean up the module level (`//!`) rustdocs for all public modules.
I claim uniform is better than any specific method/style. I tried to fit
in with what ever was either most sane of most prevalent, therefore
attaining uniformity without unnecessary code churn (one exception being
the changes to headings described below).
Notes:
* Headings - use heading as a regular sentence for all modules e.g.,
```
//! Bitcoin network messages.
```
as opposed to
```
//! # Bitcoin Network Messages
```
It was not clear which style to use so I picked a 'random' mature
project and copied their style.
* Added 'This module' in _most_ places as the start of the module
description, however I was not religious about this one.
* Fixed line length if necessary since most of our code seems to follow
short (80 char) line lengths for comments anyways.
* Added periods and fixed obvious (and sometimes not so obvious)
grammatically errors.
* Added a trailing `//!` to every block since this was almost universal
already. I don't really like this one but I'm guessing it is Andrew's
preferred style since its on the copyright notices as well.
This code was unmaintained, is unlikely to work on the majority of systems
(since it holds the whole utxoset in RAM, and not in a terribly efficient
manner), and has a dependency on `eventual` which has been broken for a
long time.
The library no longer compiles on nightly because of this, and without any
known usecases for `UtxoSet`, nor good ability to test it, I'm simply
removing the code.
I recommend anyone who cares about this extracts the code from the previous
commit and creates a new crate. It should be more featureful anyway, e.g.
support a backing store.