Performance tweaks, consistency changes

- Always trying to add Images property to existing collections
- Prefer indexers vs GetValue/GetAttributeValue
- Prefer Manager.Current.Now vs DateTime.Now (uses TimeZone from
settings)
- DataTypes.Type vs "Type"
- Removed unused loading of website when converting to HTML
- Use GetSource vs DynamicContext.Query (leaks ObjectCotnext if not
disposed)
- Optimized searching for Page Id when passing Page Name