added java.lang.Math-functions pow, hypot, round, expm1 and trivial identities
Remove Math/pow rules until we can add metadata

to them. Math/pow always returns a Double, where (* x y) will return a
Long if x and y are both Long. Once we have metadata available we can
add a comment warning people about this and add the Math/pow
transformations back in.
Merge branch 'javalangmath-fns'