Made a start with showing foreignkeys in column list.

Not finished, need to decide what to do with multiple and multi column fkeys.

pglab/PgConstraintContainer.h

@@ -12,6 +12,7 @@ public:
 
 	virtual std::string getLoadQuery() const override;
 	//std::vector<PgConstraint> getIndexesForTable(Oid table_oid) const;
+	const PgConstraint* getFKeyForTableColumn(Oid relid, int16_t attnum) const;
 protected:
 	virtual PgConstraint loadElem(const Pgsql::Row &row) override;
 };