Change UnityEngine namespace requirements

Added the concept of QueryUniqueEntity, but don't rely on it, I am still making up my mind on it. If I keep it, it will be confined to EntityStructs only
Added more ECS common components

clean up code

clean up code

much more profiler info when the ENABLE_PLATFORM_PROFILER is on

experimenting with implementor parameters by default set to null to promote the use of entity structs for building entities

improve logs

Egid doesn't need to expose the long value anymore
Added a lot more debug informations
Added a new SwapEntityGroup that declare explcitly (by contract) which group the entity must be before the swap

fixed use of PlatformProfiler
I decided to support empty EntityViewStruct

make EnginesRoot dispose itself