SCons examples

Hi,

this patch adds SCons examples to the "Shootout". All problems pass with "success" on my side (SCons 2.3.1, Python 2.7.3, Ubuntu LTS 12.04)...
There is no script for "pool", it's not really applicable since SCons knows only one "stage"...building at full throttle. ;)
Also the "monad" examples look a little wild, but it really needs a lot of trickery to force a completely different dependency handling onto SCons...only to satisfy the given test setup (one wouldn't actually model the build like this).

Best regards,

Dirk