add support for set_vector for fix external in c-library, python and unittest

doc/src/Library_utility.rst

@@ -8,7 +8,11 @@ functions.  They do not directly call the LAMMPS library.
 - :cpp:func:`lammps_decode_image_flags`
 - :cpp:func:`lammps_set_fix_external_callback`
 - :cpp:func:`lammps_fix_external_set_energy_global`
+- :cpp:func:`lammps_fix_external_set_energy_peratom`
 - :cpp:func:`lammps_fix_external_set_virial_global`
+- :cpp:func:`lammps_fix_external_set_virial_peratom`
+- :cpp:func:`lammps_fix_external_set_vector_length`
+- :cpp:func:`lammps_fix_external_set_vector`
 - :cpp:func:`lammps_free`
 - :cpp:func:`lammps_is_running`
 - :cpp:func:`lammps_force_timeout`
@@ -43,11 +47,31 @@ where such memory buffers were allocated that require the use of
 
 -----------------------
 
+.. doxygenfunction:: lammps_fix_external_set_energy_peratom
+   :project: progguide
+
+-----------------------
+
 .. doxygenfunction:: lammps_fix_external_set_virial_global
    :project: progguide
 
 -----------------------
 
+.. doxygenfunction:: lammps_fix_external_set_virial_peratom
+   :project: progguide
+
+-----------------------
+
+.. doxygenfunction:: lammps_fix_external_set_vector_length
+   :project: progguide
+
+-----------------------
+
+.. doxygenfunction:: lammps_fix_external_set_vector
+   :project: progguide
+
+-----------------------
+
 .. doxygenfunction:: lammps_free
    :project: progguide