Cosmetic change. NAME is a bit misleading whe it can consist entirely of digits.
We figure out how to ignore unmused token rather than interning them.
Eliminate more unnecessary atom creation.

All regression tests pass.
Don't make the parser do more work than it needs to on CVS-NT attributes.

All regression tests pass.
Fix passing of executable bit and add a regression test for it.
Retire the Bloom-filtering code.

It wasn't really effective.  This was masked by the fact that an optimization
dleonard patched in at the same time - computing parent links with on O(n)
merge rather than an O(n**2) comparison) is extremely effective.  By removing
the Bloom filtering we actually decrease working set and increase speed.

All regression tests pass.
Report the correct total in merge progress