Portugal is NAU! v2.5

No more Porto, Farol and etc. Found solution for Great Explorers only for Portugal.

Revised ships upgrades, and other minor tweaks.

As a big commercial ship made Nau Bigger and only one instead of two.

updated "Casa da Índia" to "Lusíadas", merging the two.

Fixed additional leaders' colors.
Navigation School or University can be built, they are mutually exclusive. And Navigation School gives one Great Explorer point instead of Great Admiral.
Fixed cannot recruit Great Admiral.