Complex-Math: Handle Operations with Scalars

First feature from @BeyondEspresso 's pull #597.

Updated the complex-math library in the radiation-plugin to handle all basic calculations (+,-,*,/) and assignment from scalars.
@BeyondEspresso 
Shoud be:
```
return Complex_T(lhs.real - rhs.real, lhs.imaginary - rhs.imaginary);
```