I've found that I often use dwarf-mode with relatively small test
files.  In this situation, it's handy to be able to expand all the
DWARF, rather than moving to each "..." separately and using C-u C-m.

This patch implements this feature.  It also makes a couple of other
minor changes:

* I removed a stale FIXME from dwarf-mode.  In practice I find I often
  use "g" to restore the buffer to a pristine state; checking the file
  mtime would work against this.

* I tightened the regexp in dwarf-insert-substructure.  This prevents
  the C-m binding from trying to re-read a DIE which has already been
  expanded.

* Finally, I've bumped the dwarf-mode version number so that this
  version can easily be installed using package.el.

2023-02-09  Tom Tromey  <tromey@adacore.com>

	* dwarf-mode.el: Bump version to 1.8.
	(dwarf-insert-substructure): Tighten regexp.
	(dwarf-refresh-all): New defun.
	(dwarf-mode-map): Bind "A" to dwarf-refresh-all.
	(dwarf-mode): Remove old FIXME.