* Updates to the cygwin build.
the dna.c file used to be generated with a full path. Cygwin doesn't like
this. The problem was with some cflags and linkflags that are used to build
makesdna.exe
Hos nicely pointed this out and proposed a solution.
Now, these flags are only added to the command when the platform != 'cygwin'.
* Updated some variables in SConstruct.