Templates

For operations such as copy&paste or placing Structures or Modules on Blueprints one had to be very careful regarding what state of a Structure is copied.
For example when copying a Belt, the Belt‘s direction should be copied, but its cooldown and Items should be ignored and default initialized.
This was pretty error prone. Since it was often not clear whether a ’real’ copy or only a simple one as described above should be performed.
I therefore introduced new Template types for every Structure that only contains the values one would expect to be copied in those cases.
In case of the Belt this now looks like this:

pub struct Belt {
    dir: Dir,
    input: Option<Item>,
    output: Option<Item>,
    last_offer: InputOutput,
    cooldown: u32,
}


pub struct BeltTemplate {
    dir: Dir,
}

This way it becomes impossible to accidentally copy the input or output of a Belt, when the cursor now holds StructureTemplate instead of Structure.
I also added conversion functions to allow for easy usage:

impl From<BeltTemplate> for Belt {
    ...
}

impl From<&Belt> for BeltTemplate {
    ...
}