[fpc-pascal] Patch: new XML export for FCL-DB readyforinclusion, issue 19790 - includes Delphi Clientdataset

[Ludo Brands]

> After my recent adventures with LazUpdater, back to the XML export.
> 
> I've written new tests with more data types that at least 
> produce test output now.
> 

Problems so far:

TClientDataSet:
- ftWideString has zero length by default: Delphi 6 returns invalid
parameter for WIDTH="0" when opening the tclientdataset. Added FieldDef.Size
:= 255; for ftWideString field definition; 

-Access 2000:
- access doesn't accept the empty value for ftAutoInc. TAutoIncField is read
only and BufDataSet doesn't do anything with autoincrement fields. Better
drop it from the test.
- access falls over the guid not being a real guid. It aborts reading the
remainder of the line because dataset not in edit/insert mode anymore ...
Guid has to be a string of the form {9F5FBC24-EFE2-4f90-B498-EC0FB7D47D15}
- ftWideString creates sometimes non ascii characters at the end. This is
not the case for TClientDataSet. Still looking in that one; 
- the year 0001 is imported as 2001. Also manually you can't enter the year
0001 in access 2002. It always becomes 2001. 

Ludo