Czech (cs) translation completed (#681)

* Update translation template file

- regenerated adarkroom.pot using pybabel

* Add script for POT recompilation

* Complete Czech translation (cs)

- finished czech translation
- converted into JS
- added language entry into langs.js

Co-authored-by: santen <tadeas.cipro@kinet.cz>

lang/langs.js

@@ -1,4 +1,5 @@
 var langs = {
+	'cs':'czech',
 	'de':'deutsch',
 	'el':'ελληνικά',
 	'en':'english',