ob_start() call made in wrong place

I was investigating in my application, why once we instantiate an phpGSB object, the output can't be sent using echo then.
The reason: is ob_start() in the start of phpGSB file.
As I see output buffering is used to handle debug information, so I moved it to such places in class.

Also I removed closing tag (because of known reasons)

Can it be merged to master @samcleaver ?