mv *.am lib/am

[Tom Tromey]

I've moved all the *.am files into lib/am.  I also move a lot of
helper files into lib/.  This turned out to be a *lot* more work than
I thought it would be.

The result still isn't perfect.  Right now we have INSTALL and COPYING
duplicated: they are both at the top level (for automake itself) and
in lib (for the test suite and installation).  I'm not really sure
what to do about this.

Akim, I applied a variant of your patch.  Some minor tweaks turned out
to be necessary.

I set up the files in lib and lib/am so that history is preserved but
tags are not.  This means that checking out the 1.4 branch will do the
right thing.

Tom