Add 'history' command to changelog; tweak ProfileVersion.__eq__().

- Add mention of the new history command to the changelog.

- Make ProfileVersion.__eq__() compare version but not path, so that it lines up
  with what __lt__() does, for simplicity.

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## 0.2.4 (unreleased)
 
+- Added an `nvd history` command for diffing successive generations of a
+  profile, issue #18.  Big thanks to Felix Uhl for the idea and implementation!
+
 - Added `--sort` option for controlling the order packages are listed in, for
   issue #17.
 

src/nvd

@@ -126,7 +126,7 @@ class ProfileVersion:
         if not isinstance(other, ProfileVersion):
             return NotImplemented
 
-        return self._version == other._version and self._path == other._path
+        return self._version == other._version
 
     def path(self):
         return self._path