Clay OnHover callback is incorrectly a global #17
Description
This is not dependent on the release mode as #14 says it is.
When using multiple calls to clay.OnHover(...) with more than one function pointer passed in the last one is the only one that is used.
This is not the case if I use the c implimentation directly by calling clay.C.OnHover directly.
This can be seen by providing multiple callbacks that print a static string when triggered.
This appears to be caused by storing the on_hover_cb globally since Clay waits until Layout time to actually do the callbacks.