Preprocess Text: Refactor

[nikicc]

Text version

2.4.dev

Expected behavior

Refactor preprocess text GUI to make in smaller and more Orange-like: methods in dropdowns, regex input filed besides and greyed out when not relevant, no ON/OFF buttons, just control area, ...

[ajdapretnar]

I vote for making Preprocess Text the way Preprocess is done in Orange. This will allow much greater flexibility + creating custom preprocessing pipeline is essential for text mining.
Widget should display a sample of preprocessed tokens in control area.

[ajdapretnar]

[gengyabc]

And I find the widget download all the files in main thread, which makes me thought my computer is dead. Could the file download moved to other thread?

[ajdapretnar]

@gengyabc I think it is best to open a separate issue for this.

Main issue implemented in #506.