add default templates to STL containers + rudimentary unit tests

Cython/Includes/libcpp/deque.pxd

 cdef extern from "<deque>" namespace "std" nogil:
-    cdef cppclass deque[T]:
+    cdef cppclass deque[T,ALLOCATOR=*]:
         cppclass iterator:
             T& operator*()
             iterator operator++()

Cython/Includes/libcpp/list.pxd

 cdef extern from "<list>" namespace "std" nogil:
-    cdef cppclass list[T]:
+    cdef cppclass list[T,ALLOCATOR=*]:
         cppclass iterator:
             iterator()
             iterator(iterator &)

Cython/Includes/libcpp/map.pxd

 from .utility cimport pair
 
 cdef extern from "<map>" namespace "std" nogil:
-    cdef cppclass map[T, U]:
+    cdef cppclass map[T, U,COMPARE=*,ALLOCATOR=*]:
         cppclass iterator:
             pair[T, U]& operator*()
             iterator operator++()

Cython/Includes/libcpp/unordered_set.pxd

 from .utility cimport pair
 
 cdef extern from "<unordered_set>" namespace "std" nogil:
-    cdef cppclass unordered_set[T]:
+    cdef cppclass unordered_set[T,HASH=*,PRED=*,ALLOCATOR=*]:
         cppclass iterator:
             T& operator*()
             iterator operator++()

Cython/Includes/libcpp/vector.pxd

 cdef extern from "<vector>" namespace "std" nogil:
-    cdef cppclass vector[T]:
+    cdef cppclass vector[T,ALLOCATOR=*]:
         cppclass iterator:
             T& operator*()
             iterator operator++()

tests/run/libcpp_all.pyx

@@ -107,3 +107,12 @@ cdef int ieps = numeric_limits[int].epsilon()
 cdef int iqnan = numeric_limits[int].quiet_NaN()
 cdef int isnan = numeric_limits[int].signaling_NaN()
 cdef int iinf = numeric_limits[int].infinity()
+
+#API checks for containers with std::allocator declared
+from libcpp.memory cimport allocator
+
+cdef libcpp.vector.vector[int,allocator[int]] vec_alloc_int = libcpp.vector.vector[int,allocator[int]](10,1)
+assert vec_alloc_int.size() == 10
+
+cdef libcpp.list.list[int,allocator[int]] list_alloc_int = libcpp.list.list[int,allocator[int]](10,1)
+assert list_alloc_int.size() == 10