Log Message:
Update liblangtag to 0.6.0.

0.5.8 -> 0.6.0
=================
Akira TAGOH (20):
      Initialize databases just once.
      Fix a build fail when --enable-debug
      Support BCP47-like locale representation
      Add deprecation macros
      Use deprecation macros
      Add a lookup table to catch up a script/language from language/script
      Update to add more files into .gitignore
      Fix the behavior on lt_tag_transform() according to tr#35
      Fix a segfault if no territory or script is given to \ 
lt_tag_convert_from_locale_string()
      Add missing header file
      Add lt_db_set_val() to change the place of database
      Fix memory leaks
      missing gobject function for lt_relation_db thing
      Support the language alias for the canonicalization
      Fix lt_trie_keys() not working
      Fix OOM handling
      Improve the bootup time
      Get rid of deprecated macro
      Add docs
      Update the library versioning