Issue 6545 - [CTFE] Hard-coded array operations not yet supported

Refactor array op generation and always generate a D version of the array operation.  In the interpreter, if a FuncDeclaration with no body is encoutered, use the D version if it is an array operation.
Merge pull request #694 from yebblies/issue6545

Issue 6545 - [CTFE] Hard-coded array operations not yet supported