The French artist Henri Matisse once cleverly described the image of a straight line as “a dot that went for a walk.” That’s the idea behind Gregory Vajda’s piano concerto, heard this evening with the Maestro’s son, the talented Vince Vajda, at the keyboard. Also on the program are delightful, art-inspired miniatures by Jean Françaix and Ottorino Respighi, as well as The Battle of the Huns, among Franz Liszt’s most stirring tone poems for full orchestra.