* Making Commands match what UntaggedValue needs
* WIP
* WIP
* WIP
* Moved to expressions for conditions
* Add 'each' command to use command blocks
* More cleanup
* Add test for 'each'
* Instead use an expression block
The extra newline character makes it hard to use nu as part of an
external processing pipeline, since the extra character could taint the
results. For example:
```
$ nu -c 'echo test | xxd'
00000000: 7465 7374 test
```
versus
```
nu -c 'echo test' | xxd
00000000: 7465 7374 0a test.
```
* WIP: move to bytes codec
* Progress on adding collect helpers
* Progress on adding collect helpers
* Add in line splitting back to lines
* Lines outputting line primitives
* Close to ready?
* Finish fixing lines
* clippy fixes
* fmt fixes
* removed unused code
* Cleanup a few bits
* Cleanup a few bits
* Cleanup a few more bits
* Fix failing test with corrected test case
This improves incremental build time when working on what was previously
the root package. For example, previously all plugins would be rebuilt
with a change to `src/commands/classified/external.rs`, but now only
`nu-cli` will have to be rebuilt (and anything that depends on it).
