add PowerSort interface

app/src/main/java/de/uni_marburg/powersort/PowerSort.java

@@ -0,0 +1,26 @@
+package de.uni_marburg.powersort;
+
+import java.util.Comparator;
+
+class PowerSort<T> {
+    /**
+     * Sorts the given range, using the given workspace array slice
+     * for temp storage when possible. This method is designed to be
+     * invoked from public methods (in class Arrays) after performing
+     * any necessary array bounds checks and expanding parameters into
+     * the required forms.
+     *
+     * @param a        the array to be sorted
+     * @param lo       the index of the first element, inclusive, to be sorted
+     * @param hi       the index of the last element, exclusive, to be sorted
+     * @param c        the comparator to use
+     * @param work     a workspace array (slice)
+     * @param workBase origin of usable space in work array
+     * @param workLen  usable size of work array
+     * @since 1.8
+     */
+    static <T> void sort(T[] a, int lo, int hi, Comparator<? super T> c,
+                         T[] work, int workBase, int workLen) {
+        assert c != null && a != null && lo >= 0 && lo <= hi && hi <= a.length;
+    }
+}