Just when you thought that freedom of expression could not become any more farcical in Singapore, the police install a CCTV at Hong Lim Park.   Already, public speaking is banned in Singapore, a group of 5 or more persons gathered to "support or oppose the views of any person" require a permit (that the police categorically state they will not grant), and even one person conducting a protest can be considered an illegal assembly and ordered to disperse. Freedom of expression is strictly confined to Speakers' Corner. On Tuesday this week, however, workmen were seen installing surveillance cameras at the venue.