Em dash functionality

[mduvall]

Change -- into — when editing content.

[abitdodgy]

Might also be nice to add support for En Dash. -- to an en dash and --- to an em dash? I'm not sure how Medium handles that.

[jamienk]

http://sujeetgholap.github.io/typesmart.js/ Check it out its pretty good

[mduvall]

@abitdodgy Looks like Medium converts all to em dash, will go with that.

@jamienk Thanks! This looks useful