Add the `WordCountable::lines()` method that returns an iterator over
lines of a file-like object. This mirrors the
`std::io::BufRead::lines()` method, with some minor differences due to
the particular use case of `wc`.
This commit also creates a new module, `countable.rs`, to contain the
`WordCountable` trait and the new `Lines` struct returned by `lines()`.
* cat: Unrevert splice patch
* cat: Add fifo test
* cat: Add tests for error cases
* cat: Add tests for character devices
* wc: Make sure we handle short splice writes
* cat: Fix tests for 1.40.0 compiler
* cat: Run rustfmt on test_cat.rs
* Run 'cargo +1.40.0 update'
* wc: Don't read() if we only need to count number of bytes
* Resolve a few code review comments
* Use write macros instead of print
* Fix wc tests in case only one thing is printed
* wc: Fix style
* wc: Use return value of first splice rather than second
* wc: Make main loop more readable
* wc: Don't unwrap on failed write to stdout
* wc: Increment error count when stats fail to print
* Re-add Cargo.lock
- refactor internal version specifications to be ">=M.m.p" (where M.m.p is *already published*)
## [why]
Loosening internal version dependencies decreases the coupling between packages such
that packages can be published in a looser order. It allows the packages to be version
updated and published in tandem (ie, by using `cargo workspace ...`). Once published,
the internal versions can then be updated (again, to an *already published* package
version), as needed.
