Cocoa: Fix some key events not being emitted

The key combinations Cmd+Period, Ctrl+Tab and Ctrl+Esc are not passed to
the first responder as key events.

This commit catches and claims these specific key events via the key
equivalents mechanism and emits them from there instead.

Closes #1362
Fixes #2278

CONTRIBUTORS.md

diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index 26e0400..6b453e7 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -6,6 +6,7 @@
 video tutorials.
 
  - Bobyshev Alexander
+ - Alzathar
  - Laurent Aphecetche
  - Matt Arsenault
  - Takuro Ashie
@@ -235,6 +236,7 @@
  - Ed Ropple
  - Aleksey Rybalkin
  - Mikko Rytkönen
+ - saikyun
  - Riku Salminen
  - Yoshinori Sano
  - Brandon Schaefer

README.md

diff --git a/README.md b/README.md
index 7e640c3..ed18b95 100644
--- a/README.md
+++ b/README.md
@@ -129,6 +129,8 @@
  - [Win32] Removed support for Windows XP and Vista (#2505)
  - [Cocoa] Added `QuartzCore` framework as link-time dependency
  - [Cocoa] Removed support for OS X 10.10 Yosemite and earlier (#2506)
+ - [Cocoa] Bugfix: Cmd+Period, Ctrl+Tab and Ctrl+Esc key events were not emitted
+   (#1362,#2278)
  - [Wayland] Bugfix: The fractional scaling related objects were not destroyed
  - [Wayland] Bugfix: `glfwInit` would segfault on compositor with no seat (#2517)
  - [Wayland] Bugfix: A drag entering a non-GLFW surface could cause a segfault

src/cocoa_window.m

diff --git a/src/cocoa_window.m b/src/cocoa_window.m
index 1769f79..6104980 100644
--- a/src/cocoa_window.m
+++ b/src/cocoa_window.m
@@ -599,6 +599,34 @@
     _glfwInputKey(window, key, [event keyCode], GLFW_RELEASE, mods);
 }
 
+- (BOOL)performKeyEquivalent:(NSEvent *)event
+{
+    // HACK: Some key combinations are consumed before reaching keyDown:
+    //       so we claim those events and emit them here
+    const int key = translateKey([event keyCode]);
+    const int mods = translateFlags([event modifierFlags]);
+
+    if (mods & GLFW_MOD_CONTROL)
+    {
+        if (key == GLFW_KEY_TAB || key == GLFW_KEY_ESCAPE)
+        {
+            _glfwInputKey(window, key, [event keyCode], GLFW_PRESS, mods);
+            return YES;
+        }
+    }
+
+    if (mods & GLFW_MOD_SUPER)
+    {
+        if (key == GLFW_KEY_PERIOD)
+        {
+            _glfwInputKey(window, key, [event keyCode], GLFW_PRESS, mods);
+            return YES;
+        }
+    }
+
+    return [super performKeyEquivalent:event];
+}
+
 - (void)scrollWheel:(NSEvent *)event
 {
     double deltaX = [event scrollingDeltaX];