- minimal rust version is now 1.48
- updated documentation
- more tests
- deprecated the `try_` prefix usage as it created ambiguities with
  other potential `try_` versions (like try and don't panic if out of
  bounds or try and don't panic if allocation fails).
- some missing methods and trait implementations (e.g. `drain)
- fixed bug in `Vec1.splice()` which caused the code to return
  a `Size0Error` in a very specific edge case where it should
  have panicked due to a out of bounds range like `Vec.splice()`
  does.