This has been mostly done with changes in the datetime crate's suddenly
supporting locales.
It's still important that the user's locale is touched only once and
cached from that point on, so a struct in output::details has been made
public, along with that module. This will change later as that object
gains more and more uses thoughout the codes.
Use the `locale` crate as a dependency to read in the set
thousands-separator character, and pass this to the file size column,
which uses it to add the separators in.
en_GB uses ","
fr_FR uses "" and just displays the numbers in one go.
- 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.
