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.

src/lib.rs

@@ -8,6 +8,7 @@ extern crate gtk_sys;
 #[allow(unused_imports)]
 #[macro_use] // only for tests
 extern crate maplit;
+extern crate regex;
 extern crate serde;
 extern crate xkbcommon;
 
@@ -17,6 +18,8 @@ pub mod float_ord;
 pub mod imservice;
 mod keyboard;
 mod layout;
+mod locale;
+mod locale_config;
 mod outputs;
 mod popover;
 mod resources;