3.0 inflector

`hyphenate()` can be useful for e.g. in a custom inflected route which generates hyphenated instead of underscored words.
@thaJeztah The second replacement being a simple str_replace isn't going to add any noticeable overhead and the code is already clean enough. I am too lazy to add a new method without any significant benefit. If you feel strongly enough about it you can make a PR later on.