Separate new() and new_with_app_id() (#841)

* Add new() and new_with_app_id()

* fix calls

* ugh

* Add comment to new()

Copied from the steamworks rs docs.

lightyear/src/connection/client.rs

@@ -165,7 +165,7 @@ impl NetConfig {
             } => {
                 let client = super::steam::client::Client::new(
                     steamworks_client.unwrap_or_else(|| {
-                        Arc::new(RwLock::new(SteamworksClient::new(config.app_id)))
+                        Arc::new(RwLock::new(SteamworksClient::new_with_app_id(config.app_id)))
                     }),
                     config,
                     conditioner,

lightyear/src/connection/server.rs

@@ -158,7 +158,7 @@ impl NetConfig {
                 // TODO: handle errors
                 let server = super::steam::server::Server::new(
                     steamworks_client.unwrap_or_else(|| {
-                        Arc::new(RwLock::new(SteamworksClient::new(config.app_id)))
+                        Arc::new(RwLock::new(SteamworksClient::new_with_app_id(config.app_id)))
                     }),
                     config,
                     conditioner,

lightyear/src/connection/steam/steamworks_client.rs

@@ -19,9 +19,9 @@ impl std::fmt::Debug for SteamworksClient {
 }
 
 impl SteamworksClient {
-    /// Creates and initializes the Steamworks client. This must only be called
-    /// once per application run.
-    pub fn new(app_id: u32) -> Self {
+    /// Creates and initializes the Steamworks client with the specified AppId.
+    /// This must only be called once per application run.
+    pub fn new_with_app_id(app_id: u32) -> Self {
         let (client, single) = steamworks::Client::<ClientManager>::init_app(app_id).unwrap();
 
         Self {
@@ -31,6 +31,20 @@ impl SteamworksClient {
         }
     }
 
+    /// Creates and initializes the Steamworks client. If the game isn’t being run through steam
+    /// this can be provided by placing a steam_appid.txt with the ID inside in the current
+    /// working directory.
+    /// This must only be called once per application run.
+    pub fn new() -> Self {
+        let (client, single) = steamworks::Client::<ClientManager>::init().unwrap();
+
+        Self {
+            app_id: client.utils().app_id().0,
+            client,
+            single: SyncCell::new(single),
+        }
+    }
+
     /// Gets the thread-safe Steamworks client. Most Steamworks API calls live
     /// under this client.
     pub fn get_client(&self) -> steamworks::Client<ClientManager> {