Conflict with new num::Float::epsilon

[cuviper]

Just a heads up -- we recently added Float::epsilon in rust-num/num#231, and then a Crater run showed that simple_gaussian broke due to call ambiguity. See the logs here:
https://tools.taskcluster.net/task-inspector/#WJwHtMdHQmikycmFEZGd3Q/0

The ambiguous call is in your gen<F>, where F::epsilon could now either mean Float::epsilon or your Epsilon::epsilon. You could change it to a more explicit call to one of these choices. Or since you seem to just be extending Float, you might remove your epsilon.

[mitchmindtree]

@cuviper thanks for the heads up!