Tolerance area for mouseover zoom

[Niklas-Peter]

If you want to see the edges of the picture you have to move the mouse exactly to the edge of the zoomed image. In this issue https://github.com/jackmoore/zoom/issues/36 you wrote, that it is too complex for you to add such a feature.

See the pull request, I hope I did it the right way, have no experience in using Github

[rizhenkov]

Maybe I was solved that issue. See that commit at my fork: https://github.com/riartem/zoom/commit/08df1b5c490203ed55a0ce20874d430a3d725bf9 (I already created pull-request, but I don't know, how many times needed the Author before merge.)