Update to prompt_toolkit 2

Created by: Zaharid

prompt_toolkit is the library we use for making interactive shells. It was recently changed to an incompatible version. The main reason for changing the code, apart from keeping up, is that it allows to work with the latest version of IPython.

To make the process of updating less boring, I have added a hardly usable feature of autocompleting by keyword in vp-comparefits. To be able to use it, you need to add vp.nnpd.science to your .netrc file.