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.
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.
