Support simple macros

Simple macros are intended to workaround C# limitations regarding inheritance

- `structs` do not support inheritance. However the rationale behind this ("Structs are supposed to be small") does not hold. in AL what is seen is multiple structs end up with exactly the same source
- Lack of multiple inheritance. Often, delegation is better. However delegation may run counter to correct API design. A simple example of this is the SAK (Swiss army knife) dilemma, where a set of utility functions needs to be redefined over and over because multiple inheritance is not allowed.

There isn't a goal to provide complex macros here. If that's ever wanted consider integrating the C preprocessor.