* Implemented --indicator-style flag on ls.
* Rust fmt
* Grouped indicator_style args.
* Added tests for sockets and pipes.
Needed to modify util.rs to add support for pipes (aka FIFOs).
* Updated util.rs to remove FIFO operations on Windows
* Fixed slight error in specifying (not(windows))
* Fixed style violations and added indicator_style test for non-unix systems
This PR adds the options to customize what information is shown in long format regarding author, group & owner. Specifically it adds:
- `--author`: shows the author, which is always the same as the owner. GNU has this feature because GNU/Hurd supports a difference between author and owner, but I don't think Rust supports GNU/Hurd, so I just used the owner.
- `-G` & `--no-group`: hide the group information.
- `-o`: hide the group and use long format (equivalent to `-lG`).
- `-g`: hide the owner and use long format.
The `-o` and `-g` options have some interesting behaviour that I had to account for. Some examples:
- `-og` hides both group and owner.
- `-ol` still hides the group. Same behaviour with variations such as `-o --format=long`, `-gl`, `-g --format=long` and `-ogl`.
- They even retain some information when overridden by another format: `-oCl` (or `-o --format=vertical --format=long`) still hides the group.
My previous solution for handling the behaviour where `-l1` shows the long format did not fit with these additions, so I had to rewrite that as well.
The tests only cover the how many names (author, group and owner) are present in the output, so it can't distinguish between, for example, author & group and group & owner.
Previously if no --color argument was input, we would always print
colors in the output. This breaks `configure` scripts which run `ls`
and then compare the output against what they expect to see, since the
left side has ANSI escape sequences and the right side doesn't.
Instead, only print escape sequences if a TTY is present, or if
`--color=always` is specified.
Fixes#1638.
