[fpc-devel] FPDoc improvements

[Marco van de Voort]

In our previous episode, Michael Van Canneyt said:
> Meanwhile I have a simple example using 2 units floating around somewhere.
> It took me lots of time to find it, but now I know where the cause is.
> Solving it is another matter entirely.

I've been thinking about it, and following the compilers way of working is
the only solution.

If you want to resolve identifiers like a compiler, you have to build scopes
like a compiler, and do that in the right order.

Otherwise funny things will happen with duplicate identifiers.