Add English catkeys to the Makefile

We can't force people to learn German... :)

src/Makefile

@@ -138,7 +138,7 @@ OPTIMIZE := SOME
 # 	will recreate only the "locales/en.catkeys" file. Use it as a template
 # 	for creating catkeys for other languages. All localization files must be
 # 	placed in the "locales" subdirectory.
-LOCALES = de
+LOCALES = de en
 
 #	Specify all the preprocessor symbols to be defined. The symbols will not
 #	have their values set automatically; you must supply the value (if any) to