Add support for optional parameters

Author: botder

Diff for: functions/Cursor/showCursor.yaml

@@ -16,6 +16,7 @@ shared: &shared
       type: 'bool'
       description: |
         A boolean value determining whether to disable controls whilst the cursor is showing. *true* implies controls are disabled, *false* implies controls remain enabled.
+      default: 'true'
   returns:
     description: |
       Returns *true* if the player's cursor was shown or hidden successfully, *false* otherwise. 

Diff for: schemas/function.yaml

@@ -100,6 +100,15 @@ $defs:
         description:
           type: string
           description: Describe the usage, contraints and other useful information about the parameter.
+        default:
+          type: string
+          description: |
+            The default value for this parameter, if none was given in the call to the function.
+            This property automatically implicitly marks this parameter as optional.
+        optional:
+          type: boolean
+          default: false
+          description: If set to true, this parameter will be marked as optional.
 
   returns:
     type: object