Turkish business dynasties accused of backing "post-modern coup"

* Prominent business families accused of links to ouster * Case highlights long-standing tensions in Turkish elite * Shares in Dogan and Koc fall sharply (Recasts with comment from lawyer, details) By Humeyra Pamuk and Nick Tattersall ISTANBUL, Sept 13 (Reuters) - A lawyer accused two of Turkey's corporate dynasties on Friday of backing the 1997 military overthrow of its first Islamist-led ...