reduce piece size

core/src/main/groovy/com/muwire/core/files/FileHasher.groovy

@@ -17,12 +17,12 @@ class FileHasher {
 	 * @return the size of each piece in power of 2
 	 */
 	static int getPieceSize(long size) {
-		if (size <= 0x1 << 25)
-			return 18
+		if (size <= 0x1 << 27)
+			return 17
 		
-		for (int i = 26; i <= 37; i++) {
+		for (int i = 28; i <= 37; i++) {
 			if (size <= 0x1L << i) {
-				return i-7
+				return i-10
 			}
 		}