I add this feature for using uwsgi websocket with gevent more easy and

convenient.

Example: tests/websockets_chat_2.py

Add:    add a new API `uwsgi.input_object()` for get `struct wsgi_req *`
in python.

Modify: `uwsgi.websocket_send/send_binary/recv/recv_nb` now has a
kwarg: `uwsgi_input`.

If not provide the `uwsgi_input` keyword argument, The four function's
behavior not changed.

When provide the `uwsgi_input` keyword argument, The four function will
get `wsgi_req` from the argument.

In this way, uwsgi websocket functions can be used in other greenlets.

plugins/python/uwsgi_python.h

@@ -100,6 +100,19 @@ typedef struct uwsgi_Input {
         struct wsgi_request *wsgi_req;
 } uwsgi_Input;
 
+
+// this struct is used for:
+// get this object in python,
+// and pass back to uwsgi.
+// uwsgi verify whether this is a valid `struct wsgi_request *` pointer
+typedef struct uwsgi_InputIdentity {
+    PyObject_HEAD
+    int mywid;
+    uint64_t requests;
+    struct wsgi_request *wsgi_req;
+} uwsgi_InputIdentity;
+
+
 struct uwsgi_python {
 
 	char *home;
@@ -307,6 +320,8 @@ void uwsgi_python_set_thread_name(int);
 				return PyErr_Format(PyExc_SystemError, "you can call uwsgi api function only from the main callable");\
 			}
 
+struct wsgi_request *py_current_wsgi_req_from_input(PyObject *);
+
 #define uwsgi_pyexit {PyErr_Print();exit(1);}
 
 #ifdef __linux__