Additions and Changes
- Moved JsonResult from Lib.AspNetCore.Mvc.JqGrid.Core.Json to Lib.AspNetCore.Mvc.JqGrid.Core.Results
- Upgraded to ASP.NET Core 3.0.0
- Rewritten default JSON features implementation to System.Text.Json
- Provided Newtonsoft.Json based JSON features as a separated package (Lib.AspNetCore.Mvc.JqGrid.NewtonsoftJson)