Make LKSL.Generics.Collections.pas compatible with FreePascal

[LaKraven]

Certain aspects of the Generics Collections unit are specific to Delphi, and IFDEFs are needed to accommodate FreePascal.

The following are already known not to exist natively in FreePascal (and will likely need custom implementations just as TStopwatch did):

• IEqualityComparer does not exist in FPC
• TEnumerable does not exist in FPC
• TPair does not exist in FPC

Note that the above might exist in FPC, but in units with different names.

[LaKraven]

It builds now, however it does not function the same way as under Delphi... mainly because of the lack of hash comparison on FreePascal's equivalent of TDictionary (which is TFPGMap)

Solution is to completely redevelop TLKDictionary to stand alone, and not use either TDictionary or TFPGMap at all.

Similarly, I should remove any use of IEqualityComparer, TEnumerable and TPair, or reimplement all of the above as part of the LKSL itself.