Option to export methods using lape-style wrappers from plugins.

Added the **option** to use lape-style (export) wrapper-functions in plugins.
By avoiding using the FFI, functions ...
- avoids leaking the result, if the result is an array.
- has around 5 times less call overhead

To export lape-style wrapper functions an ekstra kw have to be added at
the end of each function-string: `external;`.

EG:
> procedure SomeFunc(const Params: PParamArray; const Result: Pointer); cdecl; export;
    ...

Exporting:
> ProcAddr := @SomeFunc;
> StrPCopy(ProcDef, 'function SomeFunc(Size:Int32): TIntegerArray; external;');

That is how we know that we should not use the FFI.

----
It's only a small change, that does not affect anything that's already exists.