Prevent downloading songs that are already loaded. (base: fluddokt/opsu/76778f8)

- All beatmap set IDs are now stored in a set in OsuGroupList.
- OsuParser now checks the directory name for beatmap set IDs if the OsuFile doesn't contain one (for older beatmap formats).

Tweaks:
- Clear completed downloads when hitting "Import All".
- Call Download.updateReadSoFar() upon starting downloads instead of waiting for user to hover over the button (causing an unnecessary delay).

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/states/DownloadsMenu.java

@@ -438,6 +438,12 @@ public class DownloadsMenu extends BasicGameState {
 					if (index >= nodes.length)
 						break;
 					if (DownloadNode.resultContains(x, y, i)) {
+						DownloadNode node = nodes[index];
+
+						// check if map is already loaded
+						if (OsuGroupList.get().containsBeatmapSetID(node.getID()))
+							return;
+
 						SoundController.playSound(SoundEffect.MENUCLICK);
 						if (index == focusResult) {
 							if (focusTimer >= FOCUS_DELAY) {
@@ -445,7 +451,6 @@ public class DownloadsMenu extends BasicGameState {
 								focusTimer = 0;
 							} else {
 								// start download
-								DownloadNode node = nodes[index];
 								if (!DownloadList.get().contains(node.getID())) {
 									DownloadList.get().addNode(node);
 									node.createDownload(server);
@@ -515,6 +520,7 @@ public class DownloadsMenu extends BasicGameState {
 						}
 					}
 
+					DownloadList.get().clearDownloads(Download.Status.COMPLETE);
 					importThread = null;
 				}
 			};