input should not be an empty string

[brumar]

Hello,
Very nice stuff there :). I may use it a lot in the future !
On my machine, r.text_entry does not open rofi.
I managed to fix it by replacing at line 506
input="" by input=" " as for some reasons, the empty string was not fed to rofi. I investigated further by inspecting the source code of subprocess.py. Indeed, if input is falsy, stdin is closed.
source : https://github.com/python/cpython/blob/master/Lib/subprocess.py#L1489 . This is off-subject, but to me, this is a weird design choice. I don't understand why they wrote if not input and not if input is None.

Installation details :
Ubuntu 16.04.1 LTS
rofi -v : Version: 0.15.11
python3.5