Change: include fmt.h C++ headers in stdafx.h

This to prevent compilation issues between runs with and without precompiled
headers. Also remove the headers from the rest of the code base as they are
not needed there anymore, although they do relatively little harm.

Fix: Encountering two-way red signals could prune unrelated branches.

The intermediate node branch is now only pruned if the node is on the
path leading to the two-way red signal.

Remove: performance measurements in YAPF

YAPF was constantly measuring its performance, but only at
certain debug-levels this information was shown.

Now after years, I sincerely wonder if anyone still knows about this
feature and who still use it. Especially with the new framerate window,
this detailed performance is not as meaningful anymore as it once
was.