Merge amethyst#2029

2029: Bugfix/initialize pausable system data r=distransient a=azriel91

## Description

Run `System::setup` for pausable systems' delegate.

## PR Checklist

By placing an x in the boxes I certify that I have:

- **n/a** Updated the content of the book if this PR would make the book outdated.
- [x] Added a changelog entry if this will impact users, or modified more than 5 lines of Rust that wasn't a doc comment.
- [ ] Added unit tests for new code added in this PR.
- [x] Acknowledged that by making this pull request I release this code under an MIT/Apache 2.0 dual licensing scheme.

If this modified or created any rs files:

- [x] Ran `cargo +stable fmt --all`
- [x] Ran `cargo clippy --all --features "empty"`
- [x] Ran `cargo test --all --features "empty"`


Co-authored-by: Azriel Hoh <[email protected]>

amethyst_core/src/system_ext.rs

@@ -4,7 +4,7 @@
 //! functions.
 
 use crate::{
-    ecs::prelude::{Read, System},
+    ecs::prelude::{Read, System, World},
     shred::{RunningTime, SystemData},
 };
 
@@ -131,4 +131,10 @@ where
     fn running_time(&self) -> RunningTime {
         self.system.running_time()
     }
+
+    fn setup(&mut self, world: &mut World) {
+        Self::SystemData::setup(world);
+
+        self.system.setup(world);
+    }
 }

docs/CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog][kc], and this project adheres to
 ## [Unreleased]
 
 ### Added
+
 - Implement `Debug` for `ProgressCounter` and `ProgressCounterTracker`. ([#1973])
 - Added a custom render pass Example. ([#1904])
 - Add an entry for `examples/tiles` to the examples readme. ([#1978])
@@ -42,6 +43,7 @@ The format is based on [Keep a Changelog][kc], and this project adheres to
 - Tilemap rotation was incorrect and not transposed. Fixed and uses component rotation. ([#1974])
 - `Config` types no longer require a `Default` impl ([#1989])
 - Fixed Incorrect path for sprite_camera_follow example ([#2004])
+- Run `System::setup` for pausable systems' delegate. ([#2029])
 
 ### Security
 
@@ -58,6 +60,7 @@ The format is based on [Keep a Changelog][kc], and this project adheres to
 [#1989]: https://github.com/amethyst/amethyst/pull/1989
 [#2005]: https://github.com/amethyst/amethyst/pull/2005
 [#2004]: https://github.com/amethyst/amethyst/pull/2004
+[#2029]: https://github.com/amethyst/amethyst/pull/2029
 
 
 ## [0.13.3] - 2019-10-4