+ fcl-db/dbase: (Visual) FoxPro fixes:
+ initial read support for Visual FoxPro
* annotated file structures, constants etc
* better error reporting:
  different message for valid header but 
	invalid field definitions
* refactored some procedures for readability



git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24139 3ad0048d-3df7-0310-abae-a5850022a9f2