Remove readline from requirements.txt

[exploide]

This might be quite the opposite of #55 but I would like to propose removing readline from requirements.txt.

I had trouble installing this module on a recent Fedora machine and the readme for readline (https://pypi.org/project/readline/) claims that "THIS PACKAGE IS DEPRECATED".

Instead, one should use gnureadline, which installs correctly. However, the readme of gnureadline (https://pypi.org/project/gnureadline/) explains "do you really need this package in 2019? You typically don’t".

Instead, one should take a look at the standard library readline module (https://docs.python.org/2.7/library/readline.html), which apparently has the same module interface and looks compatible.

In order to avoid troubles while installing deprecated third party readline module, I propose to remove this from requirements.txt.

[epinna]

That sounds reasonable, thanks.