Rename snippet using → useout, Add useint.

snippets/c++-mode/useint

@@ -0,0 +1,5 @@
+# -*- mode: snippet -*-
+# name: useint
+# key: useint
+# --
+using std::${1:u}int${2:16}_t;

snippets/c++-mode/useout

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: using std output streams
-# key: using
+# key: useout
 # --
 using std::cout;
 using std::cerr;