dbx (database abstraction)

core routines: Marc Boeren (marc@guidance.nl)
mysql support: Marc Boeren
odbc support:  Marc Boeren
pgsql support: Rui Hirokawa (hirokawa@php.net)
mssql support: Marc Boeren
fbsql support: Frank M. Kromann (frank@frontbase.com)
initial oci8 support: Marc Boeren
