CVS and snapshots now require running autogen.sh

[Jim Blandy <jimb at red-bean dot com>]

We've changed the way we handle generated files in the Guile source
repository.  As a result, the procedure for building trees obtained
from the nightly FTP snapshots or via CVS has changed:
- You must have appropriate versions of autoconf, automake, and
  libtool installed on your system.  See README for info on how to
  obtain these programs.
- Before configuring the tree, you must first run the script
  `autogen.sh' at the top of the source tree.

The Guile repository used to contain not only source files, written by
humans, but also some generated files, like configure scripts and
Makefile.in files.  Even though the contents of these files could be
derived mechanically from other files present, we thought it would
make the tree easier to build if we checked them into CVS.

However, this approach means that minor differences between
developer's installed tools and habits affected the whole team.
So we have removed the generated files from the repository, and
added the autogen.sh script, which will reconstruct them
appropriately.


Right now, Guile's autogen.sh doesn't run configure for you, as some
autogen.sh scripts do.