Make the structs public by default

src/lib.rs

@@ -1,7 +1,7 @@
 #[macro_export]
 macro_rules! system {
     ($name:ident $pat:tt { $($rest:tt)* } ) => {
-        struct $name;
+        pub struct $name;
         impl<'a> specs::System<'a> for $name {
             type SystemData = args_to_systemdata!($pat);
             fn run(&mut self, args_to_pat!($pat): Self::SystemData) {
@@ -12,7 +12,7 @@ macro_rules! system {
         }
     };
     ($name:ident $pat:tt { $($rest:tt)* } finally { $($finally:tt)* }) => {
-        struct $name;
+        pub struct $name;
         impl<'a> specs::System<'a> for $name {
             type SystemData = args_to_systemdata!($pat);
             fn run(&mut self, args_to_pat!($pat): Self::SystemData) {