Zig requires alignment to be specified when specifying a fill character,
as otherwise digits specified after ':' are interpreted as part of the
field width.

The missing alignment specifier caused character codes < 0x10 to be
serialized incorrectly, producing an export file ncdu could not import.

For example, a character with code 1 would be serialized as '\u00 1'
instead of '\u0001'.

A directory of test files can be generated using:

    mkdir test_files; i=1; while [ $i -le 255 ]; do c="$(printf "$(printf "\\\\x%02xZ" "$i")")"; c="${c%Z}"; touch "test_files/$c"; i=$((i+1)); done

Behavioral changes:
- A single wildcard ('*') does not cross directory boundary anymore.
  Previously 'a*b' would also match 'a/b', but no other tool that I am
  aware of matches paths that way. This change breaks compatibility with
  old exclude patterns but improves consistency with other tools.
- Patterns with a trailing '/' now prevent recursing into the directory.
  Previously any directory excluded with such a pattern would show up as
  a regular directory with all its contents excluded, but now the
  directory entry itself shows up as excluded.
- If the path given to ncdu matches one of the exclude patterns, the old
  implementation would exclude every file/dir being read, this new
  implementation would instead ignore the rule. Not quite sure how to
  best handle this case, perhaps just exit with an error message?

Performance wise, I haven't yet found a scenario where this
implementation is slower than the old one and it's *significantly*
faster in some cases - in particular when using a large amount of
patterns, especially with literal paths and file names.

That's not to say this implementation is anywhere near optimal:
- A list of relevant patterns is constructed for each directory being
  scanned. It may be possible to merge pattern lists that share
  the same prefix, which could both reduce memory use and the number of
  patterns that need to be matched upon entering a directory.
- A hash table with dynamic arrays as values is just garbage from a
  memory allocation point of view.
- This still uses libc fnmatch(), but there's an opportunity to
  precompile patterns for faster matching.

The other files were already indirectly referenced, but it's good to
make it explicit.

Based on #204.

I wasn't planning on (publicly) keeping up with Zig master before the
next release, but it's looking like 0.10 will mainly focus on the new
stage2 compiler and there might not be any significant language/stdlib
changes. If that's the case, might as well pull in this little change in
order to increase chances of ncdu working out of the box when 0.10 is
out.

Fixes #199.
That's not to say it handles variation selectors or combining marks
well, though. This is kind of messy. :(

While it's true that the root item can't be a special, the first item to
be added is not necessarily the root item. In particular, it isn't when
refreshing.

Probably fixes #194

Because, even in 2022, there are systems where the libc locale is not,
in fact, UTF-8. Fixes #186.

Change "eigth-block" to "eighth-block"

Broken in 7d290595

That *usually* doesn't take longer than a few milliseconds, but it can
take a few seconds for some extremely large dirs, on very slow computers
or with optimizations disabled. Better display a message than make it
seem as if ncdu has stopped doing anything.

And also adjust the graph width calculation to do a better job when the
largest item is smaller than the number of columns used for the graph,
which would previously draw either nothing (if size = 0) or a full bar
(if size > 0).

Fixes #172.

Fixes #181, now also for Zig.

Fixes #185

Fixes #183

I'm tagging this as a "stable" 2.0 release because the 2.0-beta#
numbering will get confusing when I'm working on new features and fixes.
It's still only usable for people who can use the particular Zig version
that's required (0.9.0 currently) and it will certainly break on
different Zig versions. But once you have a working binary for a
supported arch, it's perfectly stable.

...by making sure that Context.parents is properly initialized to null
when not scanning to RAM.

Fixes #179.

Port of 96a92319

Bit pointless to make these options nullable when you never assign null
to them.

Introduced in 53d3e4c1

Not going to bloat the help output with all those settings...

Saves about 15k on the binary size. It does allocate a bit more, but it
also frees the memory this time.

+ reorder manpage a bit, since the scan options tend to be more relevant
than all those UI options.

Again, these are mainly useful with a config file.

Might as well keep it. The quick-config menu popup idea can always be
implemented later on, we're not running out of keys quite yet.