Feature: languages

added a language feature. messages are located in the foldr.messages package (files messages.properties or messages._lang_country.properties) as a key=value mapping (value being the String to display)

See the Lg class (name should be changed I guess) for general use and Lg.Utils for utilities (constructing a menu to change language basically). The list of supported languages is stored in the file named languages.

A tutorial on how does internationalization works is available here: http://docs.oracle.com/javase/tutorial/i18n/

GUI is defined in the MainWindow class. It should be merged with Liz's work separately.