UI: Capitalize "Python" in UI messages, and 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 first "domain" (typo).

@@ -1566,1 +1564,3 @@
-                           "on file reload and undo");
+                           "Layer Override Protection",
+                           "Protected layers in overridden instances are restored to "
+                           "their original settings on file reload and undo");

@@ -3488,0 +3487,4 @@
+  RNA_def_property_ui_text(
+      prop,
+      "Use Plane Trim",
+      "Limit the distance from the offset plane that a vertex can be affected");

@@ -1019,3 +1019,3 @@
   prop = RNA_def_property(srna, "use_path_follow", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", CU_FOLLOW);
-  RNA_def_property_ui_text(prop, "Follow", "Make curve path children to rotate along the path");
+  RNA_def_property_ui_text(prop, "Follow", "Make curve path children rotate along the path");

@@ -1035,3 +1035,3 @@
                            "Stretch",
                            "Option for curve-deform: "
-                           "make deformed child to stretch along entire path");
+                           "make deformed child stretch along entire path");

@@ -1052,2 +1052,3 @@
                            "Option for paths and curve-deform: "
-                           "apply the curve radius with path following it and deforming");
+                           "apply the curve radius to objects following it "
+                           "and to deformed objects");

@@ -2958,3 +2958,3 @@
   prop = RNA_def_property(srna, "falloff_curve", PROP_POINTER, PROP_NONE);
   RNA_def_property_pointer_sdna(prop, NULL, "curfalloff");
-  RNA_def_property_ui_text(prop, "Falloff Curve", "Custom light falloff curve");
+  RNA_def_property_ui_text(prop, "Falloff Curve", "Custom falloff curve");

@@ -3872,2 +3872,3 @@
   prop = RNA_def_property(srna, "target_layer", PROP_STRING, PROP_NONE);
-  RNA_def_property_ui_text(prop, "Layer", "Grease Pencil layer assigned to the generated strokes");
+  RNA_def_property_ui_text(
+      prop, "Layer", "Grease Pencil layer to which assign the generated strokes");

@@ -9959,3 +9959,3 @@
       prop,
       "Attribute Domain",
-      "Attribute domain where the attribute domain is stored in the simulation state");
+      "Attribute domain where the attribute is stored in the simulation state");

@@ -559,3 +559,3 @@
              "\n"
              "   Return the identifiers of collection members\n"
-             "   (matching pythons dict.keys() functionality).\n"
+             "   (matching Python's dict.keys() functionality).\n"

@@ -594,3 +594,3 @@
              "\n"
              "   Return the identifiers of collection members\n"
-             "   (matching pythons dict.items() functionality).\n"
+             "   (matching Python's dict.items() functionality).\n"

@@ -601,3 +601,3 @@
              "\n"
              "   Return the group indices used by this vertex\n"
-             "   (matching pythons dict.keys() functionality).\n"
+             "   (matching Python's dict.keys() functionality).\n"