Change the MacOS preference suffix to .macosx

Previously, preferences suffixed with .macos were treated specially,
but the default preferences.txt used .macosx.

I couldn't find when or how this was broken exactly - it seems
Processing used .macosx but this code was reimplemented for Arduino in
commit 33f5c53 (Implemented OS specific preferences) using .macos.

The effects of this have not been tested on OSX, but this might fix some
problems caused by wrong defaults on OSX.

Author: matthijskooijman

Diff for: app/src/processing/app/helpers/PreferencesMap.java

@@ -109,7 +109,7 @@ public void load(InputStream input) throws IOException {
 
         key = processPlatformSuffix(key, ".linux", Base.isLinux());
         key = processPlatformSuffix(key, ".windows", Base.isWindows());
-        key = processPlatformSuffix(key, ".macos", Base.isMacOS());
+        key = processPlatformSuffix(key, ".macosx", Base.isMacOS());
 
         if (key != null)
           put(key, value);