define PDL_BAD_CODE C macro during compilation of PP BadCode

PP BadCode is often almost identical to PP Code, and it makes sense to
reuse the same code whenever possible.  This macro aids in that.
Support ExtUtil::Depends by making PDL::Install::Files.
Test, implement support for "use Inline with=>q(PDL)".
Doc better Inline interface.
Update docs for release.
Dynaloader unload DLL if Win32 - thanks Sisyphus.
Update MANIFEST.