Fix various typos

Found via  codespell v2.0.dev0  
```
codespell -q 3 -I ../rawtherapy-whitelist.txt -S ./rtdata/languages -L bord,hist,fo,reall,bloc,alph,dof,thre,makro,chang,currentry,portugues,vektor,ue
```

rtgui/toolbar.h

@@ -65,7 +65,7 @@ protected:
     ToolMode current;
     bool allowNoTool;
     bool editingMode;  // true if the cursor is being used to remotely edit tool's values
-    bool blockEdit; // true if edit tool shoudn't be disabled when pressing hand button or h/H key
+    bool blockEdit; // true if edit tool shouldn't be disabled when pressing hand button or h/H key
     sigc::connection  handConn;
     sigc::connection  wbConn;
     sigc::connection  cpConn;