Add more compatibility to lessc.inc.php

Enable a working version of setVariables and modify the constructor definition.
Adding missing function setVariable

That's what I get for trying to poach things one at a time and edit in the online editor...
Remove compression option

I had this hardcoded in my version, but removed it for compatibility.
Merge pull request #73 from fabrizim/master

Add more compatibility to lessc.inc.php