* Update `.clang-format` defaults.
* Enable `AlignConsecutiveMacros`, newly supported by clang-format 9.
We often followed this style before using clang-format, and I believe
that it produces generally positive changes.
* Apply clang-format changes.
* Replace `_FITS` and `_NEXT_ALIGN` macros. clang-format didn't damage
them, it just brought them to my attention. These macros weren't
improving clarity, and the code is more systematic without them.
(For the time being, I have refrained from further overhauling the
metaprogramming here.)
Stephan T. Lavavej