[lazarus] Delphi and FPC compatible LCL version

[Marco van de Voort]

> 
> The LCL is based on the FCL and the RTL of FPC.
> At the moment, it is possible with less than a hundred IFDEFs to support the
> Delphi units, but this will become a mess, as soon, as the LCL supports
> threads, widestrings, better localization, dynamic libs and more platforms.
> So, in fact, the LCL is bound to the units provided by FPC.
> 
> According to the mails, the main reason to support the Delphi compiler, is
> to use the LCL with existing Delphi code, which can't be compiled with fpc.
> My question: What features are not supported by FPC 1.9, are portable and
> can be used with the LCL?

A lot of subsystems (like packages , variants and widestrings) aren't 100%
complete in FPC.

For the rest FPC is complete except the non-portable dispatch interface.

Only other major thing I can think of is that Delphi can link to C++, and FPC needs the
C++ to be C level wrapped first.