improved compatibility  of the swipes scripts

minSwipeDistance, swipeRadius now take a percentage of the screen's
height to calculate a distance independant of the device's resolution.

Replaced some [SerializedField] attributes to public.
Added a Die Method and a new character state

CharacterState has new state, EnumDeath
PlatformerCharacter2D has a new Die() method which uses the new Death
state to execute code before the level is reloaded (play animations,
disable characters movements ...)
Added a switch case to EnumDeath