fix: image tint color

Image used in multiple places have same tint color. This patch creates
copy before tint image to have the possibility to use different colors.

Change-Id: I8dea84e283660b67a124c96d2ff42dc198eb8b97
Reviewed-by: Andreas Traczyk <andreas.traczyk@savoirfairelinux.com>

src/views/NSColor+RingTheme.mm

@@ -120,7 +120,7 @@ return [NSColor colorWithCalibratedRed:59/255.0 green:193/255.0 blue:211/255.0 a
 
 + (NSImage*) image:(NSImage*) img tintedWithColor:(NSColor *)tint
 {
-    NSImage* image = img;
+    NSImage* image = [img copy];
     if (tint) {
         [image lockFocus];
         [tint set];