[Fluxus] racket 5.2 fix

[gabor papp]

hi,

i pushed the fix to git, which hopefully solves the problem with racket 
versions above 5.1.1.

i tested it with the latest 5.2.1 version. if you compile racket from 
source, you should not need the  '--disable-places' and 
'--disable-futures' options anymore.

please test.

best,
gabor