Apply NLL simplifications as it's now stable on the 2015 edition

Starting with today's rustc nightly 6d599337f 2019-04-22,
NLL, or more precisely two phase borrows are enabled on
the 2015 edition used by us [1].

Due to this, we can apply simplifications to the codebase
that needed two phase borrows to come to fruition.

[1]: rust-lang/rust#59114

mehlon-server/lib.rs

@@ -400,27 +400,23 @@ impl<S :NetworkServerSocket> Server<S> {
 	}
 	fn handle_players_waiting_for_kv(&mut self) {
 		let mut players_to_add = Vec::new();
-		// TODO with NLL, these {} become unneccessary
-		// See: https://github.com/rust-lang/rust/issues/57804
-		{
-			let pwfk = &mut self.players_waiting_for_kv;
-			self.map.run_for_kv_results(&mut |id, _payload, key, value| {
-				if key != "position" {
-					return;
-				}
-				if let Some((conn, nick)) = pwfk.remove(&id) {
-					let pos = if let Some(buf) = value {
-						PlayerPosition::deserialize(&buf)
-							.ok()
-							.unwrap_or_else(PlayerPosition::default)
-					} else {
-						// No value could be found
-						PlayerPosition::default()
-					};
-					players_to_add.push((conn, id, nick, pos));
-				}
-			});
-		}
+		let pwfk = &mut self.players_waiting_for_kv;
+		self.map.run_for_kv_results(&mut |id, _payload, key, value| {
+			if key != "position" {
+				return;
+			}
+			if let Some((conn, nick)) = pwfk.remove(&id) {
+				let pos = if let Some(buf) = value {
+					PlayerPosition::deserialize(&buf)
+						.ok()
+						.unwrap_or_else(PlayerPosition::default)
+				} else {
+					// No value could be found
+					PlayerPosition::default()
+				};
+				players_to_add.push((conn, id, nick, pos));
+			}
+		});
 		for (conn, id, nick, pos) in players_to_add {
 			self.add_player(conn, id, nick, pos);
 		}

mehlon-server/map_storage.rs

@@ -436,9 +436,13 @@ pub type DynStorageBackend = Box<dyn StorageBackend + Send>;
 
 fn sqlite_backend_from_config(config :&mut Config, auth_needed :bool)
 		-> Option<(DynStorageBackend, Option<SqliteLocalAuth>)> {
-	// TODO: once we have NLL, remove the "cloned" below
-	// See: https://github.com/rust-lang/rust/issues/57804
-	let p = config.map_storage_path.as_ref().cloned()?;
+	let p = config.map_storage_path.as_ref()?;
+
+	let p_config = Path::new(&p);
+	let p_auth = p_config.with_file_name(p_config.file_stem()
+			.and_then(|v| v.to_str()).unwrap_or("").to_owned()
+		+ "-auth.sqlite");
+
 	let sqlite_backend = match SqliteStorageBackend::open_or_create(&p) {
 		Ok(mut b) => {
 			manage_mapgen_meta_toml(&mut b, config).unwrap();
@@ -450,10 +454,6 @@ fn sqlite_backend_from_config(config :&mut Config, auth_needed :bool)
 		},
 	};
 	let storage_backend = Box::new(sqlite_backend);
-	let p_config = Path::new(&p);
-	let p_auth = p_config.with_file_name(p_config.file_stem()
-			.and_then(|v| v.to_str()).unwrap_or("").to_owned()
-		+ "-auth.sqlite");
 	let local_auth = if auth_needed {
 		Some(SqliteLocalAuth::open_or_create(p_auth).unwrap())
 	} else {

mehlon-server/mapgen.rs

@@ -383,11 +383,7 @@ impl MapgenMap {
 								sth_to_generate = true;
 							}
 						}
-						// TODO: once we have NLL, remove the continue, and
-						// remove the /* */ around the else below.
-						// See: https://github.com/rust-lang/rust/issues/57804
-						continue;
-					} /* else */ {
+					} else {
 						if let Some(data) = self.storage.load_chunk(pos).unwrap() {
 							let chn = MapChunk {
 								data,