Updated Portuguese translation

- New translation for errors.xml;
- Some grammatical errors have been corrected;
- General improvement of the translation;
- Changed symbols of the cardinal points ("NO" and "O" to "NW" and "W",
respectively).

<i\>You can ignore commits 297220f 3a58927 e6d7e98 if you want to. I couldn't delete those commits   :P<i>