www/trac update and python 2.7 (volunteers, if not drive-by update)

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

The version of trac in pkgsrc does not support python 3, and that is of
course increasingly less ok.  I no longer use trac, so I don't want to
put a lot of time into testing updates.

There is a 1.5.4 tag upstream, not labeled stable.  I have updated to it
locally -- just version/distinfo, changing python version logic, and
PLIST.

There are wip/trac-foo, but those are also aligned to 2.7 and some have
unfetchable distfiles.  Formally wip is not considered when maintaining
pkgsrc.

So options are:

  A) I just commit this and newer trac is then available for python3, and
     might or might not have issues, and anyone who cares can fix it.

  B) We decide nobody cares and remove it, and anyone who cares can
     re-add it.

  C) Somebody who cares speaks up and stages an update in wip and then I
  can move it to pkgsrc proper when ready.

  D) As C, but also updating wip/trac-*.

I see A as better than B; the drive-by update ought to be mostly ok.  So
I'm pruning B.  I'm fine with someone doing C and whatever of D
happening or not later.

So this is a call for anyone who wants to take on C or D.  If no one
speaks up in 7 days, I'll commit my untested update.  If you see an
additional path please feel free to mention it, of course, or anything
else.

Greg