See shape for details.
If shaper_list is not `NULL`, the specified shapers will be used in the given order, otherwise the default shapers list
will be used.
| font |
an Font to use for shaping |
| buffer |
an Buffer to shape |
| features |
an array of user specified Feature or `NULL` |
| shaper_list |
a `NULL`-terminated array of shapers to use or `NULL` |
| num_features |
the length of |
|
false if all shapers failed, true otherwise |