Adding a 'pe.close()' to getImports function to close/release mmap fi…

[mccredie]

…le descriptors.

You can't call Freeze instances twice in a row on windows because the mmap is opened on console.exe (And prevents it from being deleted or moved after the first freeze).

[schmir]

Thanks for your pull request. I'm not maintaining bbfreeze anymore and therefore won't merge it. Sorry.