Specify the version when cloning

Change-Id: I83e9f57c9ad698c2e64cea8193d0afb100338659

Change-Id: I49f31840d941348f7410d8fa52262ea06f396212

…b100338659

Improve Irrlicht instructions

…a06f396212

clang-format filesys

* Create the temp file in a temp directory. That way the OS should
  delete it in case this code does not manage to.
* Increase the amount of time between attempts to move the file.
* After all attempts fail, fall back to copying. The deletion of the
  source temporary file may fail for the same reason that MoveFileEx
  failed, but the OS should clean it up eventually.

Also add a test for it. It seemed some things in the `fs` namespace
were already tested in test_filepath, so I renamed that to test_filesys
and added the test there.

Change-Id: Idb817c3b41c7f4c81805f937e6bf467d85a4f124

…7d85a4f124

Make safeWriteToFile more likely to succeed on Windows.