Removes all items in player's inventory, when creating or first-time joining a world.

Fixes errors with sandbox scenario and instances of some mods still adding items to the player's inventory.

Mods, which load after this mod and also modify the player's inventory and thus leading to a non-empty inventory,
have to be added as optional dependencies in this mod.

Used References:
https://mods.factorio.com/mod/HardcoreStart
https://mods.factorio.com/mod/MinimalStart
https://mods.factorio.com/mod/StartWithNothing

Will deprecate as soon as one of those mods developers (preferably from "HardcoreStart") implemented all fixes this mod features (and also make it available for Factorio 0.17).