middleName consistency

[JustBlackBird]

At the moment different providers expose middle names in different ways.

For example, person provider for ru_RU locale exposes middle names with two methods: middleNameMale and middleNameFemale. At the same time, person provider for vi_VN locale exposes middle names as a single middleName method.

I suggest to use only one way of exposing middle names. To be compatible with lastName and firstName it should be done as in vi_VN locale with a single method middleName with $gender flag.

If the maintainer is interested in it I could provide a PR to fix this.

[fzaninotto]

I don't mind inconsistencies in middleNames.

[JustBlackBird]

Consider an use case when the lib is used to generate test data for multilingual system. If I use both ru_RU and vi_VN locales for testing I have to vary method name to get middle name. For example:

$faker = \Faker\Factory::create('ru_RU');
$faker->firstName(\Faker\Provider::GENDER_MALE);
$faker->middleNameMale(); // There is no "middleName" method with "gender" argument :(

but

$faker = \Faker\Factory::create('vi_VN');
$faker->firstName(\Faker\Provider::GENDER_MALE);
$faker->middleName(\Faker\Provider::GENDER_MALE);

You may notice that retrieving of middle names is inconsistent across locales.