Do not call retain on Objective-C string literals

These literals are not freed from memory and do not need to be retained.

Author: AZero13

Mac/PythonLauncher/FileSettings.m

@@ -119,7 +119,7 @@ - (id)initForFSDefaultFileType: (NSString *)filetype
     dict = [factorySettings objectForKey: filetype];
     if (dict == NULL) {
         NSLog(@"factorySettings.plist misses file type \"%@\"", filetype);
-        interpreter = [@"no default found" retain];
+        interpreter = @"no default found";
         return NULL;
     }
     [self applyValuesFromDict: dict];
@@ -134,7 +134,7 @@ - (id)initForFSDefaultFileType: (NSString *)filetype
         }
     }
     if (interpreter == NULL)
-        interpreter = [@"no default found" retain];
+        interpreter = @"no default found";
     origsource = NULL;
     return self;
 }
@@ -159,7 +159,7 @@ - (id)initForDefaultFileType: (NSString *)filetype
     self = [self initWithFileSettings: fsdefaults];
     if (!self) return self;
     interpreters = [fsdefaults->interpreters retain];
-    scriptargs = [@"" retain];
+    scriptargs = @"";
     [self applyUserDefaults: filetype];
     prefskey = [filetype retain];
     return self;

Mac/PythonLauncher/MyDocument.m

@@ -19,8 +19,8 @@ - (id)init
 
         // Add your subclass-specific initialization here.
         // If an error occurs here, send a [self dealloc] message and return nil.
-        script = [@"<no script>.py" retain];
-        filetype = [@"Python Script" retain];
+        script = @"<no script>.py";
+        filetype = @"Python Script";
         settings = NULL;
     }
     return self;