add a clang format file

[meshula]

A clang format file would be nice, perhaps we can use the one from OpenEXR as a starting point.

[KarthikRIyer]

@meshula the OpenEXR one seems to be good. I'm currently using that to format the C-bindings.

Here's the rationalTime.h file formatted using this format. https://gist.github.com/KarthikRIyer/26a14e344b1ef740dd8c95b3382ee427

I haven't taken a close look at the file yet. Are there any specific requirements that one should take care of, for such files or is it something that just works for all people.

Personally I dont like the whitespace between the function name and the parentheses.

[meshula]

the whitespace between the function name and the parentheses is a historical peculiarity of codebases that conform to old Silicon Graphics standards. I believe everyone is in agreement that the rule should be modified for OTIO to NOT have that space.

[meshula]

aside from the idiosyncratic space, the file does look nice.

[ssteinbach]

I think this issue should include:

• the clang format file (as already discussed)
• a target in the Makefile that runs the clang format in such a way that it fails if changes are needed (similar to this and the way that the python linters are run): https://stackoverflow.com/questions/22866609/can-clang-format-tell-me-if-formatting-changes-are-necessary
• a target that runs clang-format for you on the c++ files in the repo
• integrate the ^ run with make lint target-- https://github.com/PixarAnimationStudios/OpenTimelineIO/blob/e7a52a418695cb6c0407637917f23fd5b34fee60/Makefile#L100
• add them into the CI runs, next to the python linting: https://github.com/PixarAnimationStudios/OpenTimelineIO/blob/e7a52a418695cb6c0407637917f23fd5b34fee60/setup.cfg#L69
• make sure that the clang-format file goes into the right place so that IDEs like Xcode, VS, and CLion detect the file correctly