Fixed Cocoa memory leak

Cocoa/Document.m

@@ -126,6 +126,7 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
         GB_run(&gb);
     }
     [self.audioClient stop];
+    self.audioClient = nil;
     self.view.mouseHidingEnabled = NO;
     GB_save_battery(&gb, [[[self.fileName stringByDeletingPathExtension] stringByAppendingPathExtension:@"sav"] UTF8String]);
     stopping = false;

Cocoa/GBShader.m

@@ -160,6 +160,10 @@ void main(void) {\n\
     glDeleteProgram(program);
     glDeleteTextures(1, &texture);
     glDeleteTextures(1, &previous_texture);
+
+    /* OpenGL is black magic. Closing one view causes others to be completely black unless we reload their shaders */
+    /* We're probably not freeing thing in the right place. */
+    [[NSNotificationCenter defaultCenter] postNotificationName:@"GBFilterChanged" object:nil];
 }
 
 + (GLuint)shaderWithContents:(NSString*)contents type:(GLenum)type