Added 64bits detection

I like your browser detection script.
I however missed 64 bits detection.
It is very easy to add.
Here is my code
```
	 OS DETECTION
		--------------
		*/
        
        // 64 bits Detection
        $data = 'WOW64|Win64|AMD64|x86_64|x86-64|ia64|IRIX64|ppc64|sparc64|x64;|x64_64';
        if ($this->matchi_ua($data))
            $this->result_os_64bit = 'yes';
```