Backspace bugs

[y-lohse]

Right now, backspaces in grande behave a bit differently than on medium. Here's a non-exhaustive list of issues I noticed:

H1 WTF in Chrome

Carret at the start of an h1 which is preceeded by a paragraph, hit backspace; the content of the node is appended to the previous paragraph but surrounded with a <span style="font-size:2em"> (i wiish I were kidding :p)

On medium the nodes content is simply appended to the previous paragraph.

Cancelling lis

On medium, when the carret is at the start of an li and the user presses backspaces, the li is turned into a p, regardless of the content of that li or the number of surrounding lis.

In grande the behavior differs depending on the browser. Chrome usually deletes the li and appends the content to the previous tag, regardless of what that previous tag is.
Firefox has a range of different behaviors depending on whether the li contains text or not, whether it's inside and ol or ul or even the lis position in the list.

Deleting hrs

I didn't mention it in #19 but hr deletion will need adressing too. Chrome handles it rather fine, but Firefox and IE do very different (and non-sensical) things.

[mduvall]

I opened up several issues from this ticket #25, #24, #23. It will be easier if somebody would like to open a PR.

Thanks a lot for finding these!