Pypaperbot

- general improvements
- added --proxy oprion
- added --scholar-results option

Special thanks to suhan-paradkar!

Bug fix 34

- Added the possibility to specify the page range for scholar search
- Safe exit when you get blocked by scholar
- Handle bad requests from Crossref
- Other general fixes and improvements

PRs 29 28 25

General improvements
- Added a command to specify a preferred sci-hub mirror
- Closes 18 20 22

Fix

- Automatically select a working Sci-Hub link 12
- General improvements