Currently, two monolithic baby heads flank the Huntington Avenue entrance of the Museum of Fine Arts like a pair of cherubs. Do they herald a coming baby oligarchy? Or spring? In fact, neither. The cherubs bring news of two Spanish painting exhibitions: "Antonio López García" (April 11 - July 27) and "El Greco to Velázquez: Art During the Reign of Philip III" (April 20 - July 27). Antonio López García, the Spanish artist who made......