Remove reserved word

The code compiles into JavaScript with a [reserved word](http://www.w3schools.com/js/js_reserved.asp) `char`. Not sure why CoffeeScript compiler doesn't catch that, anyway, it makes YUI compressor fail:

```
'/usr/bin/java' '-jar' app/Resources/java/yuicompressor-2.4.7.jar '--charset' 'UTF-8' '-o' '/tmp/rivets' '--type' 'js' 'src/Resources/public/js/libs/rivets.js'

[ERROR] 125:15:missing variable name

[ERROR] 132:13:identifier is a reserved word

[ERROR] 133:44:identifier is a reserved word

[ERROR] 134:18:syntax error

[ERROR] 136:30:identifier is a reserved word

[ERROR] 137:18:syntax error

[ERROR] 139:15:syntax error

[ERROR] 140:19:syntax error

[ERROR] 143:13:missing ) in parenthetical

[ERROR] 143:14:syntax error

[ERROR] 145:6:missing ) in parenthetical

[ERROR] 147:11:invalid return

[ERROR] 149:3:syntax error

[ERROR] 1247:1:syntax error

[ERROR] 1:0:Compilation produced 14 syntax errors.
org.mozilla.javascript.EvaluatorException: Compilation produced 14 syntax errors.
```

I renamed `char` to `chr`
I have no idea, rivets tests passed with this version of sightglass
On Sep 21, 2014 11:17 PM, "Michael Richards" <notifications@github.com>
wrote:

> In src/parsers.coffee:
>
> >          tokens.push current
> > -        current = {interface: char, path: ''}
> > +        current = {interface: chr, path: ''}
>
> @tcz <https://github.com/tcz> I noticed in the Sightglass pull request (
> mikeric/sightglass#1 <https://github.com/mikeric/sightglass/pull/1>), you
> also changed the property names on the objects from interface to interf.
> Would that same change also be necessary here?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/mikeric/rivets/pull/377/files#r17828242>.
>