Add support for Applications (context menu) key in the Windows platform

I will add corresponding support in moonlight-qt.

src/input.cpp

@@ -1228,6 +1228,10 @@ namespace input {
       }
 
       for (auto &kp : key_press) {
+        if (!kp.second) {
+          // already released
+          continue;
+        }
         platf::keyboard(platf_input, vk_from_kpid(kp.first) & 0x00FF, true, flags_from_kpid(kp.first));
         key_press[kp.first] = false;
       }

src/platform/windows/input.cpp

@@ -516,6 +516,7 @@ namespace platf {
       case VK_LEFT:
       case VK_RIGHT:
       case VK_DIVIDE:
+      case VK_APPS:
         ki.dwFlags |= KEYEVENTF_EXTENDEDKEY;
         break;
       default: