Hello!

I've yet another commit to add on the top of the current stack of
patches already sent. This one makes it so that the source archive is
searched for the '[...].egg-info/requires.txt' file rather than check
the more common, fixed location.

This makes the importer more useful, as some packages such as
robotframework-sshlibrary use a "src" directory in their hierarchy which
would cause the previous scheme to not find requires.txt.