Implemented reduce() for Count/Min/Max Expr.
Implemented reduce() for Count/Min/Max Expr.

foam-framework/foam,jlhughes/foam,osric-the-knight/foam,foam-framework/foam,shepheb/foam,jlhughes/foam,mdittmer/foam,jacksonic/foam,jacksonic/foam,shepheb/foam,foam-framework/foam,foam-framework/foam,foam-framework/foam,jlhughes/foam,jlhughes/foam,shepheb/foam,mdittmer/foam,osric-the-knight/foam,osric-the-knight/foam,mdittmer/foam,jacksonic/foam,osric-the-knight/foam,jacksonic/foam,mdittmer/foam