Cleanup: spelling and duplicates in local dictionary

Correct some misspellings in the custom spellcheck dictionary as well
as any instances of the previous spellings in code comments.

Ref !123459

source/blender/blenloader/intern/versioning_legacy.cc

@@ -780,7 +780,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
       sound = static_cast<bSound *>(sound->id.next);
     }
 
-    /* `mesh->subdiv` changed to reflect the actual reparametization
+    /* `mesh->subdiv` changed to reflect the actual reparametrization
      * better, and S-meshes were removed - if it was a S-mesh make
      * it a subsurf, and reset the subdivision level because subsurf
      * takes a lot more work to calculate. */

source/blender/editors/interface/interface_context_menu.cc

@@ -821,7 +821,7 @@ bool ui_popup_context_menu_for_button(bContext *C, uiBut *but, const wmEvent *ev
     }
 
     /* Keying Sets */
-    /* TODO: check on modifyability of Keying Set when doing this */
+    /* TODO: check on modifiability of Keying Set when doing this. */
     if (is_anim) {
       uiItemS(layout);
 

source/blender/editors/screen/screen_ops.cc

@@ -4797,7 +4797,7 @@ static int screen_animation_step_invoke(bContext *C, wmOperator * /*op*/, const
       if (delta_frames < 1.0) {
         /* We can render faster than the scene frame rate. However skipping or delaying frames
          * here seems to in practice lead to jittery playback so just step forward a minimum of
-         * one frame. (Even though this can lead to too fast playback, the jitteryness is more
+         * one frame. (Even though this can lead to too fast playback, the jitteriness is more
          * annoying)
          */
         delta_frames = 1.0f;

tools/check_source/check_spelling.py

@@ -6,7 +6,7 @@
 """
 Script for checking source code spelling.
 
-   python3 tools/check_source/check_spelling.py some_soure_file.py
+   python3 tools/check_source/check_spelling.py some_source_file.py
 
 - Pass in a path for it to be checked recursively.
 - Pass in '--strings' to check strings instead of comments.

tools/check_source/check_spelling_config.py

@@ -199,7 +199,7 @@ dict_custom = {
     "invocated",
     "irradiance",
     "iteratively",
-    "jitteryness",
+    "jitteriness",
     "keyable",
     "keyless",
     "linearize",
@@ -220,7 +220,7 @@ dict_custom = {
     "misconfiguration",
     "misconfigured",
     "modally",
-    "modifyability",
+    "modifiability",
     "monoscopy",
     "monospaced",
     "mutators",
@@ -324,13 +324,13 @@ dict_custom = {
     "remapper",
     "remappings",
     "remesher",
-    "rendeder",
+    "renderer",
     "renderable",
     "renderers",
     "renormalize",
     "renormalized",
     "reparameterization",
-    "reparametization",
+    "reparametrization",
     "representable",
     "reprojected",
     "reprojecting",
@@ -390,7 +390,6 @@ dict_custom = {
     "symmetrize",
     "symmetrized",
     "targetless",
-    "targetless",
     "teleporting",
     "templating",
     "tertiarily",
@@ -433,13 +432,11 @@ dict_custom = {
     "undefined",
     "undeform",
     "undeformed",
-    "undeformed",
     "undersample",
     "undersampled",
     "undersamples",
     "undersampling",
     "undisplaced",
-    "undistored",
     "undistorted",
     "undistorting",
     "unduplicated",
@@ -460,7 +457,6 @@ dict_custom = {
     "unhide",
     "unintuitive",
     "unkeyed",
-    "unkeyed",
     "unkeyframed",
     "unlink",
     "unlinkable",
@@ -485,7 +481,7 @@ dict_custom = {
     "unpause",
     "unpaused",
     "unphysical",
-    "unpoision",
+    "unpoison",
     "unproject",
     "unquantifiable",
     "unreferenced",
@@ -495,7 +491,6 @@ dict_custom = {
     "unreproducible",
     "unscaled",
     "unselect",
-    "unselect",
     "unselected",
     "unsetting",
     "unshadowed",
@@ -513,7 +508,6 @@ dict_custom = {
     "unterminated",
     "untracked",
     "untransformed",
-    "untransformed",
     "untrusted",
     "untyped",
     "unusably",
@@ -627,7 +621,7 @@ dict_custom = {
     "incref",
     "increfed",
     "increfing",
-    "intelisense",
+    "intellisense",
     "jitter",
     "jittered",
     "jittering",
@@ -640,7 +634,6 @@ dict_custom = {
     "searchable",
     "segfault",
     "stdin",
-    "stdin",
     "stdout",
     "sudo",
     "threadsafe",
@@ -723,8 +716,8 @@ dict_custom = {
     "specular",
 
     # Mathematical terms.
-    "egenvalue",
+    "eigenvalue",
-    "egenvalues",
+    "eigenvalues",
 
     # Blender specific terms.
     "animsys",