add NETWORK_INFO_MULTIPLE feature (bug 948037)

close #21
replace PIL with pillow
better warning messages (bug 978204)
Merge pull request #22 from andymckay/978204

better warning messages (bug 978204)
fix string muppetry
looks like we can use the latest Pillow
Merge pull request #23 from mstriemer/drop-PIL-for-pillow

replace PIL with pillow