Improve HSTR to read input from pipe

[dvorka]

HSTR visualization and filtering might be used for use cases like

find -type f | hh

To provide functionality like fzy https://github.com/jhawthorn/fzy - simply load data from std input an then use existing history logic.

Related:

• [stdin] selected rows from the pipe are just printed (not inserted) on new kernels #235 #539 #551