Enable auto-continuation of Markdown lists in instances where the bullet is not preceded by whitespace
Fix problem with undoing after hitting enter to eliminate auto-inserted list bullet

The deletion of the bullet + whitespace character wasn't going through the proper channels, and wasn't getting registered with the undo manager. Undoing after doing that would, rather than re-insert the bullet, delete some of the adjacent characters.
Fix exception when using Mountain Lion's press-and-hold to insert a special character

Specifically, when you hit a number key (from the pop-up menu) to select which special character. I suspect this causes a nil character to be inserted, or something like that; regardless, and an exception from trying to call a non-existent isEqualToString on it was the result. Switching around the literals and the parameter is a MUCH safer approach, and fixes this exception.
Merge pull request #118 from Westacular/list-continuation

Fixes for list continuation