Internet explorer support

[mingan]

As far as I can tell the library doesn't work in IE (11, presumably older). I tracked it down to DragStart msg not being sent. I looked into it and the only reasonable place where it could happen is if the mousedown event isn't properly decoded (which fails silently in Elm). I'm on Elm 0.18 so the library delegates this work to Mouse.position still. I see, that the 0.19 version has internalized the decoding but it's still treating pageX and pageY as integers which will fail in IE (as in described elm-lang/mouse#6).

I haven't put together an example for Elm 0.19 so my first question is has anyone encountered the same behaviour?

If yes, I think the solution would be to simply decode the two attributes as floats. Apart from draggedStyle, it's not used anywhere else so the change shouldn't affect public API.