Improvements to Vi inputstream_handler.
Improvements to Vi inputstream_handler.

melund/python-prompt-toolkit,amjith/python-prompt-toolkit,jaseg/python-prompt-toolkit,niklasf/python-prompt-toolkit,Carreau/python-prompt-toolkit,ALSchwalm/python-prompt-toolkit,jonathanslenders/python-prompt-toolkit,Carreau/python-prompt-toolkit,ddalex/python-prompt-toolkit