Binding and gobject-introspection

Write this section once the vips8 Python binding is done.

If you are writing a language binding, you won't need these. Instead, make a new operation with vips_operation_new() (all it does is look up the operation by name with vips_type_find(), then call g_object_new() for you), then use vips_argument_map() and friends to loop over the operation's arguments setting them. Once you have set all arguments, use vips_cache_operation_build() to look up the operation in the cache and either build or dup it. If something goes wrong, you'll need to use vips_object_unref_outputs() and g_object_unref() to free the partially-built object.