#4 modified definition to match specifications
#4 added default implementation of the entity interface
#4 added a method to get raw data of all attributes
#4 added possibility to pass an object to the method 'set' to set multiple attributes at a time
#4 forgot to remove 'Interface' in the class name
#4 removed possibility in default entity to set attributes
#4 forgot to implement Sy.EntityInterface
#4 verif added to prevent assigning undefined as an attribute
#4 fixed setting locked attributes
#4 changed the demo entity
#4 fixed some problems around the locking
#4 changed the lock list
#4 prevent setting multiple times the same locked attribute
#4 added a 'UUID' attribute to reference (and change) the default attribute of the entity
#4 typo fix + added registering of the UUID when an entity is created
Close #4 Merge branch 'feature/entities' into develop