Experimental fix to MANIFEST

Addresses [#89436: Missing files in distribution](https://rt.cpan.org/Ticket/Display.html?id=89436)

DON'T APPLY WITHOUT CAREFUL REVIEW.

I just hacked away at stuff until things worked.  That might have removed something actually necessary.

This branch removes files from MANIFEST that are generated during distribution building.  I removed Makefile.PL code that copied files back up from the distdir and kept hacking away at Makefile dependencies until everything appeared to work.

The only change I'm really dubious about for you in the one about cpansign, but without that I couldn't test at all.

From this branch, it should be possible to do this:

    git clean -dxf
    perl Makefile.PL
    make touchtestdistros
    make dist
    make disttest
    git status

There should be no dirty files at that point.