Better use of sl::EnumHasFlag()

[r4]

This function was introduced as a nice way of working with strongly typed enum classes, without breaking the illusion of c++'s enum class (which this function ironically undoes).
There's likely a few places this function could be implemented to improve readability, and we should mark it as FORCE_INLINE to eliminate that slight overhead.
A simple regex or manual search should do the trick.

[r4]

good work me! closed in < 1 hour :D