Default chunk size reduced from 1MB to 0.5MB

src/main/java/org/qortal/arbitrary/ArbitraryDataFile.java

@@ -54,7 +54,7 @@ public class ArbitraryDataFile {
 
     public static final long MAX_FILE_SIZE = 500 * 1024 * 1024; // 500MiB
     protected static final int MAX_CHUNK_SIZE = 1 * 1024 * 1024; // 1MiB
-    public static final int CHUNK_SIZE = 1 * 1024 * 1024; // 1MiB
+    public static final int CHUNK_SIZE = 512 * 1024; // 0.5MiB
     public static int SHORT_DIGEST_LENGTH = 8;
 
     protected Path filePath;