locale: Add translations for layout names

Pulled in some Unix-specific code from https://github.com/rust-locale/locale_config to reduce dependencies.

First reason to reduce dependencies: gettext-rs is not in Debian. Copying gettext-sys might have made sense, but the interface is somewhat confusing.

For translating a couple identifiers, detection and some hand-rolled hash map is all that is needed, and the option to move to gettext later remains.

locale_config has been stripped of the lazy_static dependency, which, messing with the strtup sequence, might be a source of debugging woes. Plus setting language once in the beginning is somewhat inflexible regarding runtime changes.

data/langs/en-US.txt

@@ -0,0 +1,8 @@
+us English (US)
+de German
+el Greek
+es Spanish
+it Italian
+jp+kana Japanese (kana)
+nb Norwegian
+