added tests to check for overwriting of input

all pass, except for the inverse-real case, as is expected
inverse-real transforms now copy their input to not get clobbered
added an explicit cast to pacify the compiler
added version string to the .pd file
cleaned up comments, removed some extra {}
addded TODO file
I no longer try to make fftw plans from PDL::null data
comments
added some more explicity type tests
added readme
moved the main .pm to the middle of the generated output
more todo points