Unit upgrade

Now players can upgrade units. One of following five upgrade icons appears at the shop.
- Power: Gold 3, Power +1
- Defense: Gold 3, Defense +1
- Health: Gold 3, Health: +3
- Cost: Gold 10, Cost -1
- Range: Gold 5, Unit gains ranged.
Units can be upgraded multiple times regardless of upgrade type.
- Corrected some Portuguese sentences.
- Fixed "Fury" and "Divine power" effects do not reflect results for battle preview properly.