[0.2.4] UI rework (again), Dialogues, Introduction, ...

Added dialogues and introduction :

A good story needs some way to narrate herself, so we are introducing some beautiful, stupid and funny characters to tell the story the way we want !

Those dialogues also include a new tutorial, explained by our beloved sheriff Shelton.

Completely new UI :

We are done with the basic black/semi-transparent UI theme. Here is what it now looks like :

Enemies explanations when you encounter them for the first time :

Specifics rework :

We also included some tips about the turrets, so you can use them wisely.

Discover Pink Eye :

That is now the new boss of the map 2.

Other :

- New personality : Latecomer Jeanne.

- New capacity :  freeze time.

- Added boss bestiary.

- New ambient musics.