Fix temporary file deletion not working on Windows

See [this issue](https://github.com/junkblocker/codesearch/issues/13).

The Windows version of codesearch is broken because it doesn't properly close any of its file handles before it tries to remove the files.

My fork has [this change](https://macoy.me/code/macoy/codesearch/commit/c5f1d5ebd4e48099be0970402d5218c9fd7ac1e8) which fixes this. My fork has diverged (I added a `tempDir` argument so that I could move the temp files where I wanted them), but someone should be able to port over my changes without too much issue.