Make dates respect current locale (deprecations!)

And make comments use it in a smart way (it's not but it works)

Deprecate "extra.date_format" and "extra.comments.locale" and replace it
with "date_format" and "date_locale" in translation files

theme.toml

@@ -8,9 +8,6 @@ demo = "https://daudix.codeberg.page/duckquill"
 [extra]
 primary_color = "#9a9996"
 primary_color_alpha = "rgba(154, 153, 150, 0.2)"
-date_format = "%d %B %Y"
-issues_url = ""
-source_url = ""
 
 [author]
 name = "David Lapshin"