Is based on Google style which was used in the Libmv project before,
but is now consistently applied for the sources of the library itself
and to C-API. With some time C-API will likely be removed, and it
makes it easier to make it follow Libmv style, hence the diversion
from Blender's style.
There are quite some exceptions (clang-format off) in the code around
Eigen matrix initialization. It is rather annoying, and there could be
some neat way to make initialization readable without such exception.
Could be some places where loss of readability in matrix initialization
got lost as the change is quite big. If this has happened it is easier
to address readability once actually working on the code.
This change allowed to spot some missing header guards, so that's nice.
Doing it in bundled version, as the upstream library needs to have some
of the recent development ported over from bundle to upstream.
There should be no functional changes.
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