removal proposal: filesystems/fuse- gmailfs pcachefs wikipediafs

[Greg Troxel <gdt%lexort.com@localhost>]

These were last released by their upstreams in 2006, 2010, and 2017.

They are marked for python 2 only.  Perhaps only because they used
py-fuse-bindings which used to be 2.7 but not longer is, and because
nobody is paying attention.

I believe there are no users, and that zero people care about them.

If you object (and especially if you would like to bring them to python
3), please speak up.   Otherwise, I'll rm them after the branch is cut.

(While they are blocking dropping 27 from py-fuse-bindings, I don't
think that's a good reason to remove them.  It was a good reason to try
to visit their HOMEPAGEs and check their last release.