neuronapi: reword 'cell' to 'slot' in nrn_object_ptr_push docs

Per review: 'cell' collides with its NEURON meaning (a neuron). Use
'slot' for the Object* storage location in the docs and the matching
source comment.

Author: ec1dev

docs/capi.rst

@@ -879,13 +879,13 @@ Functions, objects, and the stack
 
 .. c:function:: void nrn_object_ptr_push(Object** obj_ref)
 
-    Push a writable object-reference cell onto the stack.
+    Push a writable object-reference slot onto the stack.
 
-    :param obj_ref: Address of the caller's ``Object*`` cell.
+    :param obj_ref: Address of the caller's ``Object*`` slot.
 
     Unlike :c:func:`nrn_object_push`, which pushes an object by value, this
-    pushes the *cell* holding the object. When the callee assigns to the
-    matching ``$oN`` argument, the assignment writes back through the cell and
+    pushes the *slot* holding the object. When the callee assigns to the
+    matching ``$oN`` argument, the assignment writes back through the slot and
     updates ``*obj_ref`` in place. This is the out-parameter form used by the
     ``h.ref(obj)`` idiom, where a function returns a value by storing it in a
     caller-supplied object reference. ("ptr", as in :c:func:`nrn_double_ptr_push`,

src/nrniv/neuronapi.cpp

@@ -318,9 +318,9 @@ void nrn_object_push(Object* obj) {
 }
 
 void nrn_object_ptr_push(Object** obj_ref) {
-    // Push a writable object-reference cell (the out-parameter form of
+    // Push a writable object-reference slot (the out-parameter form of
     // nrn_object_push). When a callee assigns to the corresponding $oN arg,
-    // hoc assigns through this cell, updating *obj_ref in place. Unlike
+    // hoc assigns through this slot, updating *obj_ref in place. Unlike
     // nrn_object_push, which pushes an object by value, this exposes the
     // h.ref(obj) idiom (a callee that writes back into the caller's objref).
     // Named for the pointer it pushes (cf. nrn_double_ptr_push); the "ref" in