* consolidate everything with the makefile, the "tidy" target now just
sets the env var that is checked for in CMakeLists
* rm clang-tidy from pre-commit as it's run as part of the "test"
makefile target later in the file anyway
* project-wide refactor to accomodate removal of "using namespace xyz"
to stop polluting top-level namespace with "std" as recommended by the
Google C++ style guide.
* use a pre-commit hook to enforce this
ref:
https://google.github.io/styleguide/cppguide.html#Namespaces
* that is, both in ci, pre-commit config and in the makefile
* makefile and ci args are a little more strict than the pre-commit ones
* use globs of the file extensions we're after
* add verbosity
