[Bug] Recent image.nvim changes throw off image positions by one

[benlubas]

There was a change (that I made too, no one to blame but me :P) in image.nvim a little bit ago that changed the way inline images are rendered in relation to their extmarks, they're now rendered one line below instead of on the same line.

Here's the offending line:

3rd/image.nvim@d24d498#diff-90b9887d8ed1bf7a314a020fe9673aacfe3778eac5198d82eafa29f3b2668dc3R153

We just need to throw a -1 in molten somewhere

this was mentioned in the comments of #88

[benlubas]

Time to take another crack at fixing this bug (in image.nvim)