This changes the way extended attributes (xattrs) are printed. Before, they were artificially printed out on their own line both in lines mode *and* details mode, which looked a bit weird. Now, they are additional 'child nodes' of that item that get printed alongside errors.
All this allows all the 'extra info' that is going to be present for very few entries to be consolidated and listed in the same way, without resorting to extra printlns.
As a great side-effect, it allows taking out some of the more redundant code in the Table impl -- it is now *always* going to be in create-child-nodes mode, as *any* file now can, not only when we have the --tree flag in use.
Also, it now actually displays errors when failing to read the extended attributes, such as if the user doesn't have permission to read them.
The extended attribute flag has been temporarily disabled while I work out the best way to do it!
Previously, each time it tried to render a table (to check its width), it both re-queried the filesystem and re-formatted the values into coloured strings.
These values are now calculated only once before the table is drawn, and are used repeatedly throughout.
Although it looks as though there's more `clone()`ing going on than before, it used to be recalculating things and storing them as vectors anyway, so the memory would still be used in any case.
This commit adds --grid, which, when used with --long, will split the details into multiple columns. Currently this is just 2 columns, but in the future it will be based on the width of the terminal.
In order to do this, I had to do two things:
1. Add a `links` parameter to the filename function, which disables the printing of the arrow and link target in the details view. When this is active, the columns get way too large, and it becomes not worth it.
2. Change the `print_table` function from actually printing the table to stdout to returning a list of `Cells` based on the table. This list then gets its width measured to calculate the width of the resulting table.
