Comparing changes

The check for `self.end() == usize::MAX` can be combined with the `self.end() + 1 > slice.len()` check into `self.en() >= slice.len()`, since `self.end() < slice.len()` implies both `self.end() <= slice.len()` and `self.end() < usize::MAX`. The tradeoff is slightly worse error reporting: previously there would be a special panic message in the `range.end() == usize::MAX` case.

Same reasoning as previous commit.

Optimize indexing slices and strs with inclusive ranges