Fix typos

Found via codespell v1.17.0.dev0  
```
codespell -q 3 -S ./ChangeLog*,*.po,./.git,./NEWS* -L als,ang,ba,chello,daa,doubleclick,foto,hist,iff,inport,klass,mut,nd,ower,paeth,params,pard,pevent,sinc,thru,tim,uint
```

app/core/gimpimage-convert-indexed.c

@@ -2781,7 +2781,7 @@ static void
 snap_to_black_and_white (QuantizeObj *quantobj)
 {
   /* find whitest and blackest colors in palette, if they are closer
-   * than 24 units of euclidian distance in sRGB snap them to pure
+   * than 24 units of euclidean distance in sRGB snap them to pure
    * black / white.
    */
 #define POW2(a) ((a)*(a))

build/windows/installer/MessageWithURL.isi

@@ -378,7 +378,8 @@ begin
 end;
 
 
-//find out if URL label has focus, draw focus rectange around it if it is, and return index of focused label
+//find out if URL label has focus 
+//draw focus rectangle around it if so and return index of focused label
 function Message_FocusLabel(): Integer;
 var	i: Integer;
 	FocusRect: TRect;

build/windows/installer/gimp3264.iss

@@ -1524,7 +1524,8 @@ DebugMsg('RemoveDebugFilesFromDir', pDir);
 	end;
 end;
 
-//remove .debug files from previous installs - there's no built-in way in Inno to recursivly delete files with wildcard+extension
+//remove .debug files from previous installs
+//there's no built-in way in Inno to recursively delete files with wildcard+extension
 procedure RemoveDebugFiles();
 var Directories: TArrayOfString;
 	Index: Integer;

plug-ins/common/tile-small.c

@@ -29,7 +29,7 @@
  */
 
 /* Change log:-
- * 0.2  Added new functions to allow "editing" of the tile patten.
+ * 0.2  Added new functions to allow "editing" of the tile pattern.
  *
  * 0.1 First version released.
  */

plug-ins/gfig/notes.txt

@@ -36,7 +36,7 @@ the only style attributes that work are foreground color and brush
 shape; others will be added shortly.
 
 When you start Gfig, and the dialog comes up, the background of the
-preview shows a represntation of the image you are working on.  Each
+preview shows a representation of the image you are working on.  Each
 time you do something in GFig, the result is reflected by a change in
 both the Gimp image and the GFig preview, so you can see in real time
 the results of everything that you do.  (The rendering could stand to