UI: Capitalize "Python" in UI messages, improve a few others

- "... (matches pythons ...)": capitalize and use possessive ('s).
- "Layer Proxy Protection": replace proxy by override, following 2.80.
- "Enable Plane Trim": expand description.
- "Make curve path children to rotate along the path": remove "to".
- "Option for curve-deform: make deformed child to stretch along
  entire path": remove "to".
- "... apply the curve radius with path following it and deforming":
  rephrase unclear description.
- "Custom light falloff curve" : unrelated to lights, used in Grease
  Pencil modifiers.
- "Grease Pencil layer assigned to the generated strokes": rephrase
  because a GP stroke is assigned to a layer, not the other way
  around.
- "Attribute domain where the attribute domain is stored in the
  simulation state": remove second "domain" (typo).

Pull Request: blender/blender#107916

source/blender/python/intern/bpy_utils_units.c

@@ -156,7 +156,7 @@ PyDoc_STRVAR(
     "   :type str_ref_unit: string or None\n"
     "   :return: The converted/interpreted value.\n"
     "   :rtype: float\n"
-    "   :raises ValueError: if conversion fails to generate a valid python float value.\n");
+    "   :raises ValueError: if conversion fails to generate a valid Python float value.\n");
 static PyObject *bpyunits_to_value(PyObject *UNUSED(self), PyObject *args, PyObject *kw)
 {
   char *usys_str = NULL, *ucat_str = NULL, *inpt = NULL, *uref = NULL;
@@ -243,7 +243,7 @@ PyDoc_STRVAR(bpyunits_to_string_doc,
              "   :type compatible_unit: bool\n"
              "   :return: The converted string.\n"
              "   :rtype: str\n"
-             "   :raises ValueError: if conversion fails to generate a valid python string.\n");
+             "   :raises ValueError: if conversion fails to generate a valid Python string.\n");
 static PyObject *bpyunits_to_string(PyObject *UNUSED(self), PyObject *args, PyObject *kw)
 {
   char *usys_str = NULL, *ucat_str = NULL;