Added up-arrow-partial-string-matching.py example.
Added up-arrow-partial-string-matching.py example.

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