Import Explorer for tables

- Fixed bug preventing to set numerical property inside "Customize Options" dialog.

- Clicking on "multiple files / lists" button and selecting only one file now uses datastore instead of readtable. This can be used to read tables with the same format from multiple spreadsheet lists in one Excel file.
- bug fixes

Added:
- more options to customize under the "Customize options (Advanced)" button

New:
- customize selected options before reading data into the workspace.

Bug fix:
- "default" didn't work on Selected Data Types when multiple files selected

Improvement:
- when preview ends with error, you can de/select variables end try to preview again

Bug fix:
- right click on "Confirm" button and selecting "default" didn't change "Selected Data Types" column into the default state

- import multiple tabular text files (.csv, .txt)

Fixed:
- bug with missing "datetime" data type

- names checking before reading into the workspace variables
- added icon

- de/select multiple variables at once with mouse, Ctrl, Shift and using context menu in the Selected Variables Column
- description updated

- About button
- error in case no variable is selected
- progress bar
- Export to workspace renamed to Read to workspace
- Update and preview renamed to Confirm selections and preview
- after changing selections you must confirm them before reading

- fixed a bug that prevented data import

Added:
- possibility to sort variables

Improved:
- user interface updated
- better selection of variables

Bug Fixes