comments on columns

Show the comments in the list of columns of a table.
Generate SQL to set them.

pglablib/catalog/PgAttribute.h

@@ -31,6 +31,7 @@ public:
 
 	QString defaultValue; ///< Comes from pg_attrdef table
 	QString sername, serschema; // serial sequence name and schema
+    QString description; ///< from pg_description
 
 	bool operator==(Key _k) const { return relid == std::get<0>(_k) && num == std::get<1>(_k); }
 	bool operator==(const QString &n) const { return name == n; }