Infix gt

[Xliff]

This pull request removes the comparator operators from DateTime::Math, since they have now been internally implemented by Rakudo.

The problem was discovered based on this error from the test suite.

==> Testing DateTime::Math
Ambiguous call to 'infix:«>»'; these signatures all match:
:(DateTime:D \a, DateTime:D \b)
:(DateTime $a, DateTime $b)
in block at t/math.t line 27

Removing the comparators seemed the easiest solution. Now all test cases pass:

ok 1 - year changed correctly, add 1d
ok 2 - month changed correctly, add 1d
ok 3 - day changed correctly, add 1d
ok 4 - year changed correctly, subtract 1y
ok 5 - month changed correctly, subtract 1y
ok 6 - day changed correctly, subtract 1y
ok 7 - DateTime - DateTime
ok 8 - from-seconds to days
ok 9 - duration-to-from() works.
ok 10 - DateTime > DateTime
ok 11 - DateTime < DateTime
ok 12 - DateTime >= DateTime
ok 13 - DateTime <= DateTime
ok 14 - DateTime == DateTime
ok 15 - DateTime cmp DateTime
ok 16 - DateTime <=> DateTime
ok 17 - DateTime != DateTime