dbquery: add option with_dict to run_sql()

• Enriches run_sql() with a new option called with_dict that returns directly list-of-dictionaries instead of tuple-of-tuples. (closes #830)
• Adds 4 regression test cases.
• Changes with_desc parameter type from integer to boolean in run_sql and run_sql_with_limit in order to keep coherence with the with_dict parameter.
• Updates miscutil-dbquery.webdoc.