Create sx-babel

Has functions and a variable for font-locking pre blocks.
Patch sx and sx-question-print to use sx-babel.
Don't require sx

Requiring sx is not needed because the macro is autoloaded.
Fix some implementation bugs
Update sx.org
Require sx-babel on sx-load
Merge pull request #141 from vermiculus/babel

Font-lock code blocks according to mode.
Autoload sx-authenticate

This also removes the sx-authenticate alias and renames
sx-auth-authenticate to sx-authenticate.

I did this because I felt it wasn't helpful to have both. Whenever I hit
`M-x sx-au <TAB>` the only completions offered were two identical, but
differently named, commands. That's useless at best, confusing at worst.
Merge pull request #147 from vermiculus/autoload-auth

Autoload sx-authenticate
Use package-file directive in Cask

No need to repeat the metadata which in sx.el: cask knows how to read it.
Update package description line
Merge pull request #148 from purcell/patch-1

Use package-file directive in Cask
Merge pull request #149 from purcell/patch-2

Update package description line

Cask can get the package description from this line.
HOTFIX: Mark question as read when displaying it.

This is a pretty big bug because it was leading SX to think the question
wasn't read, even though it was open. This, in turn, prevented the user
from being able to do anything (vote, comment) on the question, since we
prevent interaction with unread questions.
Merge branch 'master' into use-let-alist

Conflicts:
	Cask