1) Add new language definition into language_list.h

2) Copy help_english.h, extra_english.h and message_english.h into new files
   named help_<lang>.h, extra_<lang>.h and message_<lang>.h, where <lang> is
   the english name of your language.

3) In the files created in step 2, change the language they are meant for
   and translate all the text that needs to be translated. Refer to SANITY.txt
   as necessary.

4) Add include statements for help_<lang>.h, extra_<lang>.h and message_<lang>.h
   into all_help.h, all_extra.h and all_messages.h respectively. The order of
   include statements in those files is irrelevant, however for clarity try
   to keep it identical to the order in language_list.h.

5) Compile.
