Auto merge of #226 - grovesNL:class-macro, r=jdm

Use new objc class macro

This PR removes the `class` function in favor of the [new `class` macro exposed by objc](SSheldon/rust-objc#65) which caches access by class name. Note that this macro should eventually (through procedural macros) be able to link directly to the class.

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cocoa/Cargo.toml

@@ -17,4 +17,4 @@ block = "0.1"
 bitflags = "1.0"
 libc = "0.2"
 core-graphics = { path = "../core-graphics", version = "0.15" }
-objc = "0.2"
+objc = "0.2.3"

cocoa/examples/fullscreen.rs

@@ -14,7 +14,7 @@ use cocoa::appkit::{NSApp, NSApplication, NSApplicationActivationPolicyRegular,
 
 use core_graphics::display::CGDisplay;
 
-use objc::runtime::{Class, Object, Sel};
+use objc::runtime::{Object, Sel};
 use objc::declare::ClassDecl;
 
 fn main() {
@@ -44,7 +44,7 @@ fn main() {
         app_menu_item.setSubmenu_(app_menu);
 
         // Create NSWindowDelegate
-        let superclass = Class::get("NSObject").unwrap();
+        let superclass = class!(NSObject);
         let mut decl = ClassDecl::new("MyWindowDelegate", superclass).unwrap();
 
         extern fn will_use_fillscreen_presentation_options(_: &Object, _: Sel, _: id, _: NSUInteger) -> NSUInteger {