Fixed leak in wrap_shape_instance.
Fixed leak in wrap_shape_instance.

Similar to the leak in wrap_view_instance: a pointer was being
overwritten but not deallocated.  There might be similar leaks
in the other wrap functions.  I think that __new__ will call
cinit but not plain init, so only classes with cinit are potential
problems.

mkeeter/pysfml2-cython,mkeeter/pysfml2-cython