Implement level down system
Move class about Sprite to renderer.sprite.
Merge branch 'master' of https://github.com/cchampet/Java_nanowars.git

Conflicts:
	src/renderer/UnitSprite.java
Fix bug on Tower reset
Merge branch 'master' of https://github.com/cchampet/Java_nanowars.git
Add ProjectileSprite.
(use "proj_damage.png" image for all projectiles)
Merge branch 'master' of https://github.com/cchampet/Java_nanowars.git

Conflicts:
	src/engine/tower/Tower.java
	src/renderer/TowerSprite.java
Transform Projectile (in TowerAttack class) into a LinkedList
Commentary rectification
Stop the game when only IA are alive.
Fix #59
Add documentation.
Split Projectile creation  for legacy
Add ZoneTower attack
Add different projectile sprite
Fix bug on Tower reset (again)
especially on projectiles list
Some clean.
The Dispatcher knows the number of the currentLevel.
You can have several levels following.
When you finish a map, after 5s you return to the menu.
Merge branch 'master' of https://github.com/cchampet/Java_nanowars.git

Conflicts:
	src/dispatcher/Dispatcher.java

I don't add your stuff Océane, just fix the conflicts...