Revert default --graph-style to "hash"

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

ncdu.pod

@@ -230,8 +230,8 @@ the browser with the 'g' key.
 =item B<--graph-style> I<OPTION>
 
 Change the way that the relative size bar column is drawn. Recognized values
-are I<hash> to draw ASCII C<#> characters (most portable), I<half-block> to use
-half-block drawing characters (the default) or I<eighth-block> to use
+are I<hash> to draw ASCII C<#> characters (default and most portable),
+I<half-block> to use half-block drawing characters or I<eighth-block> to use
 eighth-block drawing characters. Eighth-block characters are the most precise
 but may not render correctly in all terminals.
 

src/main.zig

@@ -61,7 +61,7 @@ pub const config = struct {
     pub var show_mtime: bool = false;
     pub var show_graph: bool = true;
     pub var show_percent: bool = false;
-    pub var graph_style: enum { hash, half, eighth } = .half;
+    pub var graph_style: enum { hash, half, eighth } = .hash;
     pub var sort_col: SortCol = .blocks;
     pub var sort_order: SortOrder = .desc;
     pub var sort_dirsfirst: bool = false;