Add support for @ftype - grid feature type.

lib/jsduck/doc_parser.rb

@@ -97,6 +97,8 @@ module JsDuck
           at_type
         elsif look(/@xtype\b/)
           at_xtype
+        elsif look(/@ftype\b/)
+          at_ftype
         elsif look(/@member\b/)
           at_member
         elsif look(/@author\b/)
@@ -244,6 +246,14 @@ module JsDuck
       skip_white
     end
 
+    # matches @ftype name
+    def at_ftype
+      match(/@ftype/)
+      add_tag(:ftype)
+      maybe_ident_chain(:name)
+      skip_white
+    end
+
     # matches @member name ...
     def at_member
       match(/@member/)