Instantiation of generic classes is not possible in Kotlin
multiplatform. Thus, instead of instantiating a generic class in the
SystemService the system function gets a factory method for calling
the constructor of the system.

First version which works.

The component listener will be added together with registering the
component in the world configuration. That was done because when
registering the component listener the base type of the component is
needed. Without reflections that is not possible to detect it from the
component listener template type. Thus, adding component and listener
objects together is the most elegant workaround - I guess.

The spawner should be able to spawn objects which can spawn objects
themselves. This is needed for the meteor object. It spawns fire trails.

- It is now possible to spawn objects which themselves spawn another
objects.
- Added variation of acceleration which makes the animation of the file
trails looking more dynamic.

In case of injection of multiple dependencies with the same type it is now
possible to specify the type name on injection to the world configuration.
When passing that dependency in a system or component listener than the
type name can be given as an argument to Inject.dependency() function call.

Updated the readme to reflect that injection of dependencies is possible
by providing an optional type name as parameter together with the depencency
object.

Rigidbody and destruct components were added which are use to control
movement and destruction of entities. For that a new system called
DestructSystem was added. With it the destruction of an entity can
triger creation of new objects like explosions, etc.
Rigidbody component details will control how an entity is influenced
by gravity, friction or damping. This still needs to be implemented yet
in the MoveSystem.

Source code for Fleks ECS was moved under korge-fleks to decouple it
from the example code.
Updated fleks-ecs example code with source comments.

The equal function of BitArray was unsafe regarding comparing objects of
different type. Added unit tests to avoid regression.