Couple of changes required for my mod

Moving growing trees to separate module.
Systems can now dynamically inject new Components, prohibit adding of Components or modify Components when an entity is created.
Information about tool (item) used to destroy a block is now passed all the way down to the system that drops items when block is destroyed.
Added event that allows to draw an overlay on top of an icon in inventory.
Inventory cells can now be "ghost" - do not allow moving items into it and out of it, used only for storing and displaying an item that was clicked on it.
Starting "defaut" (most likely test) inventory now sends an event that allows to override this behaviour when event is consumed.
Moved the world entity generation to before the world initialization to allow configuring generators with events, as world entity is needed for that.