[Squirrel-sql-develop] The latest changes

A new API to add tabs to the stored proc panel
(Isession.addProcedurePanelTab).
ResultSet meta data is now available in the SQLPanel.
Table headings now appear in plugin summary dialog.
New stored proc parms and results tab.
Cleaned up the thread pool.
Object tree expansion now threaded (Johan)
Alias connection dialog now threaded (Johan)
ErrorDialog now multiline (Johan)