Fix spelling and punctuation errors in comments and documentation

Fix several occurrences of misspelling "trivial" as "trival"; use "from"
rather than "than"; add missing articles and commas.

Closes https://github.com/wxWidgets/wxWidgets/pull/874

src/common/addremovectrl.cpp

@@ -54,7 +54,7 @@ wxAddRemoveCtrl::Create(wxWindow* parent,
         return false;
 
     // We don't do anything here, the buttons are created when we're given the
-    // adaptor to use them with in SetAdaptor().
+    // adaptor to use them with SetAdaptor().
     return true;
 }