splitWithNesting, Sequence<String>.flatten(), path fix on win

src/main/kotlin/blitz/collections/BatchedUtils.kt

@@ -7,4 +7,12 @@ fun ByteBatchSequence.stringify(batch: Int = 64): Sequence<String> {
             iter.nextBytes(batch).decodeToString()
         else null
     }
+}
+
+fun Sequence<String>.flatten(): String {
+    val out = StringBuilder()
+    forEach {
+        out.append(it)
+    }
+    return out.toString()
 }