Fix deprecated use of inline properties

[rubenwardy]

Defining things directly in the entity definition table is deprecated

Instead, properties should be done like so:

initial_properties = {
    physical = true,
    collide_with_objects = true,
    collisionbox = {...},
    visual = "mesh",
    mesh = "...",
    textures = {...},
}

note: this only applies to Object Properties, as set by object:set_property()

[TheTermos]

Good point, but that requires some changes in lua, because there's an implicit assumption these properties are defined directly. Gonna pull it in as soon as that's done.

[rubenwardy]

Please note that initial_properties is only for engine properties. You shouldn't put anything in there that the engine doesn't understand, and you shouldn't access it from code - use get_properties() instead

[TheTermos]

Added support for initial_properties in init.lua. Thanks