April 15 (Reuters) - Clashes between Sudan's main paramilitary group and the armed forces on Saturday killed at least 25 people, a doctors' group said, in an apparent struggle for control amid the country's halting moves toward elections after a military coup. The Sudanese air force late on Saturday told people to stay indoors while it conducted what it called an aerial survey of RSF activity, and a holiday was declared in Khartoum state for Sunday, closing schools, banks and government offices. See here for a complete list of exchanges and delays