Some min/max functions in lib

library/math/package.scala

+package leon
+
+package object math {
+
+  def min(i1: Int, i2: Int) = if (i1 <= i2) i1 else i2
+  def max(i1: Int, i2: Int) = if (i1 >= i2) i1 else i2
+  def min(i1: BigInt, i2: BigInt) = if (i1 <= i2) i1 else i2
+  def max(i1: BigInt, i2: BigInt) = if (i1 >= i2) i1 else i2
+
+}