This change was made in 359fe90 due to recommendations from tooling.
On its face this change makes sense since it removes a copy that
isn't always necessary. In practice it caused ergonomic issues due
to now being forced to make a copy of the render states when needed.
The performance gains of eliding this copy are unsubstantiated. We
have not done any profiling to measure its impact. For lack of such
measurements I'd rather err on the side of improved user experience.
If future benchmarks prove this copy is rather expensive then we
can reconsider removing it with that evidence in mind.
While I don't suspect there are any uninitialize variable bugs
present, it's still good to err on the side of safety and provide
an initial value nonetheless.
Fixed formatting issues per review
Implemented copy constructor since operator= is implemented
Reverted operator=, add NOLINT for copy constructor per review
Fixed clang-tidy escape in examples
Fixed OSX clang-tidy escapes
