global i18n : add plantlife_i18n mod

idea taken from homedecor_modpack and its homedecor_i18n
all translated mods have a new dependency : plantlife_i18n
translations are stored in po/pot file : one file for all mods

added french translation (almost complete)
transfered de/es/tr/pt translations to corresponding .po file
(only for some mods, unfortunately translations are incomplete)