#2 Internationalyzer: imports added even if they already exist

[Francois MAROT]

When internationalizing files (this happens if a string in
the file is marked as "TO_TRANSLATE"), the
internationalizer adds 3 imports to the file:
import java.util.*;
import java.text.*;
import bambooAL.internationalization.*;

even if those import are already in the source-code,
they will be imported again...
Worst the third one may not be valid for your project...
We'll have to correct it.

TODO: check for the import and only add needed imports.