Misc. Windows fixes

I set up a virtual machine and tried some stuff out. Notably, I figured out that there is now a better way to handle blocking network access in sandboxie than before, which would crash anything that tried to create sockets whether or not it tried to access the internet.

I also figured out that #116 (closed) and #225 (closed) were being caused by something I'd done a long time ago to get the test suite to pass on windows, but it wasn't really necessary, as doubling backslashes fixed substituting windows paths into package files created as strings in the test suite, but broke normal use of backslashes. Better fixed by just using raw strings anywhere the test suite is substituting paths into the package files.