refs #74 More cleanup

- improved SQLDriver so that more default methods will work for various databases.  This was accomplished by adding quote_tabe(), quote_column() and quote_value() methods, as the largest difference between databases is between how the query strings are formatted.
- moved delete_record() to be handled by the driver
- started working on cleanup and documentation of the abstracted database concept

Author: PySimpleSQL

examples/journal_postgres.py

@@ -17,7 +17,7 @@
     [ss.selector('sel_journal','Journal',sg.Table,num_rows=10,headings=headings,visible_column_map=visible)],
     [ss.actions('act_journal','Journal')],
     [ss.record('Journal.entry_date')],
-    #[ss.record('Journal.mood_id', sg.Combo, label='My mood:', size=(30,10), auto_size_text=False)],
+    [ss.record('Journal.mood_id', sg.Combo, label='My mood:', size=(30,10), auto_size_text=False)],
     [ss.record('Journal.title')],
     [ss.record('Journal.entry', sg.MLine, size=(71,20))]
 ]