Radian

- python 3 only
- require prompt_toolkit 3.0

- a workaround when jedi crashes

- support jedi 0.18 in reticulate prompt

- enable autosuggestion
- enable toggling of autosuggestion feature via radian.auto_suggest
- add emacs keybindings to vi insert mode
- fix multiline raw string detection

- better handling reticulate python environment

- actually fix the XDG_CONFIG_HOME
- suggest user to switch radian for reticulate