Otherwise, just display the hour and minute.

Using the datetime crate, add an extra column to the --long view that
prints out the modified, accessed, or created timestamp for each file.
Also, let the user pick which one they want to see based on the --time
command-line option.

- Turn the views and main program loop into structs, rather than just as one gigantic function
- Separate views into their own files

The addition of the git column and the tree view meant that a lot of functions now just took extra arguments that didn't seem to fit. For example, it didn't really work to have only one 'view' method that printed out everything, as the different view options now all take different parameters.

FileName was always a special-cased column, as it was assumed to be the last column in the output. Now, it's explicitly marked as such. This allows the hash marks to be placed before the filename, rather than at the start of the line.

There's still a lot to do, but this is actually *something*. The tree hierarchy is displayed using hashes at the start of a line. I want to have it just before the filename, but this will need some changes to the way that columns are handled.

Now there are no more unwrap()s!

- Rename std::io to std::old_io

This is something that I've long wanted to add. It uses libgit2 as an optional dependency.

Extensions aren't ever displayed in lowercase, just compared case-insensitively, so this makes sense.

Instead of stripping the ANSI formatting characters from our strings, work out the length without them and use that. This is per-column, but most of them are simple (just the same number of characters in the non-coloured string).

Sometimes, this is really simple: for example, trwxrwxrwx permissions strings are always going to be ten characters long, and the strings that get returned are chock full of ANSI escape codes.

This should have a small benefit on performance.

- uint -> usize
- getopts Cargo library
- replace feature gates with unstable APIs

Also, remove dependency on the Regex library by replacing the one place it was used with standard code that should hopefully be faster anyway.

Different types of user caches could come in the future...

- Prefer iter over into_iter where appropriate
- Cut down on cloning

I'm serious, the more functionality I can use external crates for, the better.

Feels good turning all that code into a dependency!

I can't complain, because the breaking changes were caused by my pull request...

Yeah, I broke my own code again.

Also, re-use the stat result from directory-checking.

This finally fixes the issue where trying to list a file causes a crash. Also, tidy up some of the uses of references.

- Remove uses of to_string() on a &str where it wasn't necessary
- Use SendStr to reduce allocations further