SharedPreferences: Nit API wrapping android SharedPreferences class

A module wrapping 'android.content.SharedPreferences' allowing to load/save data to internal storage for the android platform. Some tests have been added to the mnit_simple example. 

The compiler has been slightly modified to ignore '\n' in java extern types.

As asked by @privat and @xymus to store persistant game data.
Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
Nouvel exemple puis réveillé: documenter dans l'API que fait le code suivant.

~~~
sp.add_string("cle", "valeur")
print sp.int("cle", 42)
~~~