Add Map Built Data

Add built data to the gitignore.
Includes data about a map for UE4.14 that is generated when the user builds it (surprise! :D).
Often gigabytes in size.
Definitely don't want it in your repository.

Author: calben

UnrealEngine.gitignore

@@ -56,6 +56,9 @@ Build/*
 # Don't ignore icon files in Build
 !Build/**/*.ico
 
+# Built data for maps
+*_BuiltData.uasset
+
 # Configuration files generated by the Editor
 Saved/*