Add basic support for writing minidumps

[paulkermann]

With this pull request, windbg will be able to open the dump and parse it.
Obviously, some windbg features will not work (stack trace wont work because thread context is not retrieved and !teb won't work because the teb is not retrieved), but its main functionality will (viewing memory, loaded modules, etc...).

This PR also merges your writer branch into the master.

[paulkermann]

I have written a tool that does what I have needed. It is present here

[skelsec]

Thank you for the PR. I did some tests on it and it seems to me that you left some debug prints and input calls there.
I have removed those so you don't need to bother, but it will take some more tests until I can merge this because I'd need to find a solution that allows writer to work without including PythonForWindows.
In case I can't find a better solution I'll merge this.