Expr: Add ability to define constexpr and runtime versions of functions separately.
Expr: Add ability to define constexpr and runtime versions of functions separately.

ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,fixator/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,ambrop72/aprinter,fixator/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,fixator/aprinter,ambrop72/aprinter,johnkingsley/aprinter,fixator/aprinter,johnkingsley/aprinter,fixator/aprinter,fixator/aprinter