TDbf 6.4.3 released

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V6.4.3

- fixed: delphi 3 compilation; dynamic array of restructure info (rep by kjteng)
- fixed: datetime index creation using delphi 4 (rep by agam)
- fixed: storage of negative numbers in integer fields (rep by agam)
- fixed: index corruption when opening, with emptytable (rep by arioch)
- fixed: index corruption on regenerateindexes (rep by piotr)