Misc. typos and whitespace

Found via `codespell -q 3 --skip="*.po,*.ts,./.git,./src/3rdParty,./src/CXX,./src/zipios++,./src/Mod/Assembly/App/opendcm,./ChangeLog.txt" -I ../fc-word-whitelist.txt` and `grep`. Excess whitespace auto-removed by Atom editor.

src/Mod/Fem/femobjects/_FemResultMechanical.py

@@ -65,7 +65,7 @@ class _FemResultMechanical():
     # standard Feature methods
     def execute(self, obj):
         """"this method is executed on object creation and whenever the document is recomputed"
-        update Part or Mesh should NOT lead to recompution of the analysis automatically, time consuming
+        update Part or Mesh should NOT lead to recomputation of the analysis automatically, time consuming
         """
         return