bug#14941: [Patch] Lighten up wrt version specification

[Tom Willemse]

Hey,

I said I would look at this bug and so I did. Sorry it took me so long
to undertake any action on it.

The attached merge directive/patch should take care of point #1, the
first half of #2 and point #3. Please let me know if you agree, I'll
happily fix any use cases you had in mind that still don't work.

In regard to the second half of #2, about requiring specific files,
instead of packages. How would you have package.el handle these when
downloading packages from ELPA or installing a package or file? Would
you have them skipped or would requiring a specific file prevent it from
being used in the same way? Or would the use have to make sure that file
is in their `load-path' before installing the package? What is the
use-case you have in mind?

Please let me know what you think, any comments, criticisms and
considerations would be greatly appreciated.

package-versions.txt
Description: Lighten up, patch