Make FeaturesRunner run methods in source code order

FeaturesRunner should run methods in source order. This gives reproducible builds, and is the principle of least surprise. It also helps navigate between the source code and the list of methods in the JUnit output.

It could be argued that relying on source order in the tests is a bad thing, and this is true, but this is a different problem and the convenience of seeing the test output in the same order as the source code is invaluable for debugging.