Fix for not handling mixing of @ and $

From the <a href="https://incident57.com/codekit/help.html#kit">Kit help file for CodeKit</a>:
> You can use either $ or @ to denote a variable name and you can use equals signs, colons or just a space to assign a value. 

To me this also implies that one could set a variable using dollar notation and then later reference it using the at sign or vice versa. This PR is a fix for that.

Caveat: I have not been able to test this against what CodeKit does.