Quest handling

Hello!

In the last two days I decided to add a way to handle quest in the game.
Now chapter00 isn't anymore a simple event but a collection of 3 quests.

So what actually change from the point of view of the player?
Nothing much, there's just a new tab that shows the quests and their status. (still need to improve graphics)

What change from the point of view of someone that should write a quest?

Something more.

-Firstly I added two new event steps:

StartQuest and EndQuest

both take as parameter the id of the quest (e.g. Main.Chapter00.RentHome)

-Secondly I added a way to query the state of a quest

-Lastly I added a quest definition. Which is a xml file that contain all the data pertaining the xml

So if someone would want to write a quest he has to:

1. Define the quest in the xml definition file.

2. Start the quest from an already playable point of the game.