A few cosmetics

Nothing really revolutionary this time :) Just a couple of consistency and usability improvements, f.ex. I like being able to call GetEntitySetName from my code.

> A few cosmetics
1. Function GetEdmSpaceType shouldn't belong to region "ApplyChanges Helpers"
2. Function GetEdmSpaceType must return null in case of multiple OSpace types found for entity type (more consistent with the old solution)
3. Move function GetEntitySetName to public. Add comment