eshell/pcomplete: substring completion

[Kai Grossjohann]

Is it possible to get zsh-style substring completion in
eshell/pcomplete?

zsh substring completion works like this: Say the user typed "xy" as a
filename and then hit TAB.  Then zsh looks to see if any of the
filenames starts with "xy".  If there are any, normal completion is
performed.

The interesting case, the one that I'm talking about, is that there is
no filename starting "xy".  Then zsh looks for filenames where "xy" is
a substring.  It offers all those as the list of completions, and it
also moves point to before the substring entered.

Substring completion works within directories, that is, typing
foo/bar/xy and then TAB means that the directory foo/bar is taken
as-is, and "xy" is substring-completed within that directory.

Kai