Use UVTYPE and PTR2UV() to avoid pointer size warnings on compile
Fix some implicit assumptions on gcc as the compiler

Conditionalizing the code which only works for gcc and
changing the PDL version prerequisite to 2.001 so that
actual testing can determine which version is needed.
Maybe there is some PDL version specific reason that
2.006 was required, if so, things will break in the
CPAN developers release testing.
Update VERSION to 0.02.2_01 for CPAN developers release

And remove the requirement on Alien::FFTW3 so that tests
will occur.  The Alien::FFTW3 requirement will only work
when there is an official CPAN release of that module.
Add a .gitignore
Add some more defaults to .gitignore