TDbf 6.3.1 released

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V6.3.1

- added: freepascal support, needs 1.9 (or higher)
- fixed: strange bugs due to fparser not initialized correctly, for example
with expression of different index (rep by sysklop)
- added: findrecord implemented -> find{first,next,prior,last} should now work
- fixed: index deletion bug corner case, no records left (rep by sysklop)
- fixed: repagefile creating empty index file (rep by paez)