fixed sort key calculation. postgres driver encloses bind variables in ' ' which makes the sort key calculation fail. the key calculation is done in tcl now.
fixed sort key calculations. the postgres driver puts ' ' around the bind variable. the old code performed calculations like "and sort_key = (:prev_sort_key + :next_sort_key)/2", which caused postgres to barf. this calculation is now done in tcl.
Major change.I put all database dependent parts in their directories and kept the data only in common.This is needed for the database independence and pl(pg)sql differences.
