General improvements

[joehinkle11]

Here's a list of what I've changed on my fork

• a bug fix for when you change themes on an already open editor
• a few properties made public
• a new onTextChange listener which provides details about what section of text changed
• smart dashes disabled
• a display_name field is added to the languages spec
• a new onSelectionChange listener. I think something like this already existed noticed after I implemented it. Maybe onSelectionChangeClosure should be removed before merge?

[ActuallyTaylor]

I will check this out over the weekend, after a quick glance, all looks good