link keyboard functions to each other

api/lovr/callbacks/keypressed.lua

@@ -22,6 +22,7 @@ return {
   returns = {},
   related = {
     'lovr.keyreleased',
-    'lovr.textinput'
+    'lovr.textinput',
+    'lovr.system.isKeyDown'
   }
 }

api/lovr/callbacks/keyreleased.lua

@@ -17,6 +17,7 @@ return {
   returns = {},
   related = {
     'lovr.keypressed',
-    'lovr.textinput'
+    'lovr.textinput',
+    'lovr.system.isKeyDown'
   }
 }

api/lovr/system/isKeyDown.lua

@@ -18,5 +18,9 @@ return {
       arguments = { 'key' },
       returns = { 'down' }
     }
+  },
+  related = {
+    'lovr.keypressed',
+    'lovr.keyreleased'
   }
 }