Alias underscored() to decamelize()

[jamiel]

I believe there are people looking for fooBar -> foo_bar searching for a function called decamelize() as with decapitalize() . This could be a useful alias for underscored() .

[stoeffel]

From a decamelize I would expect the API to be something like decamelize(string, [separator="_"]).
underscored doesn't take a separator and it would make no sense to change the API of underscored to take on. So in my opinion decamelize could be a new function but not an alias. If we create decamelize we should change dasherize humanize and underscored to use dasherize.

[dgolman]

@stoeffel when you refer to the changes of dasherize humanize and underscored to use dasherize do you mean to use decamelize?