Being able to drop files into the VSE is an expected feature of users ex.: http://youtu.be/jav19O_AeB8?t=257 (turn on auto-translation of subtitles if this is not a language you speak), and in consistency with ex. dropping elements into the 3d view or the image editor. So this patch does that.
This patch includes the changes in D13304, since it needs to support drag and drop of IDs too, but they can be removed at request if that patch has already been committed.
Clip art example:
