Updated pt localization files

Hi!
Please update the pt localization file with the following file:
http://mega.ist.utl.pt/~pmmm/pt.xml
Ran Auditlocale on the file and fixed missing entries; also translated all the 
already present but in english strings.
-- 
Pedro Morais -  - http://www.rnl.ist.utl.pt/~pmmm/