fix ipysheet column sort

[hndgzkn]

When the data has too many rows, the interface uses pagination. If the user sorts using ipysheet column sort, the app only sorts the visible rows which might be misleading. Either we should sort all data, or disable sorting.

[hndgzkn]

ipysheet is built on Handsontable. While initializing, column sorting is enabled by default and ipysheet provides no parameter to disable that.

Made a pull request on ipysheet to enable/disable column sorting.