Add Java support for std::unique<T> for input parameters.

This works by transferring ownership of the underlying C++ memory
from the target language proxy class to an instance of the unique_ptr
which is passed to the wrapped function via std::move.

The proxy class has a new swigRelease() method which sets the
underlying C++ pointer for the proxy class to null, so working
in much the same way as std::unique_ptr::release(). Any attempt at
using the proxy class will be the same as if the delete() function
has been called on the proxy class. That is, using a C++ null pointer,
when a non-null pointer is usually expected.

This commit relies on the previous commit that uses std::move
on the temporary variable used for the wrapped function's input parameter
as std::unique_ptr is not copyable, it has move-only semantics.

Lib/java/std_unique_ptr.i

@@ -8,19 +8,42 @@
  * ----------------------------------------------------------------------------- */
 
 %define %unique_ptr(TYPE)
+
 %typemap (jni) std::unique_ptr< TYPE > "jlong"
 %typemap (jtype) std::unique_ptr< TYPE > "long"
 %typemap (jstype) std::unique_ptr< TYPE > "$typemap(jstype, TYPE)"
 
+%typemap(in) std::unique_ptr< TYPE > (TYPE *unique_temp)
+%{ unique_temp = *(TYPE **)&$input;
+  $1.reset(unique_temp); %}
+
+%typemap(javain) std::unique_ptr< TYPE > "$typemap(jstype, TYPE).swigRelease($javainput)"
+
 %typemap (out) std::unique_ptr< TYPE > %{
    jlong lpp = 0;
    *(TYPE **) &lpp = $1.release();
    $result = lpp;
 %}
+
 %typemap(javaout) std::unique_ptr< TYPE > {
      long cPtr = $jnicall;
      return (cPtr == 0) ? null : new $typemap(jstype, TYPE)(cPtr, true);
    }
+
+%typemap(javarelease) TYPE %{
+  protected static long swigRelease($javaclassname obj) {
+    long ptr = 0;
+    if (obj != null) {
+      if (!obj.swigCMemOwn)
+        throw new RuntimeException("Cannot release ownership as memory is not owned");
+      ptr = obj.swigCPtr;
+      obj.swigCMemOwn = false;
+      obj.delete();
+    }
+    return ptr;
+  }
+%}
+
 %template() std::unique_ptr< TYPE >;
 %enddef