Clojure wrapper for java.util.Locale.

The main fn: [[locale]].

Note: wherever a Java method requires a Locale object, not only such an object,
but also a "locale specification" is accepted.
In such cases the Java method (called by the Clojure wrapper) will get
the Locale object "specified" by the "specification". This means, that
(unless we pass a Locale object already to the Clojure wrapper), the needed Locale object
is created "on the fly", "behind the scenes", inside the Clojure wrapper.

Below are the possibilities for such "**locale specifications**" and their interpretations.

* **`nil`**  
In this case the Locale object, "specified" by this "specification"
is the one returned by Java's `Locale.getDefault()`.

* a **Java Locale object**  
In this case the resulting Locale object is the same as the "specification".

* a **map** with keys corresponding to the Locale.Builder class' setXXX instance methods,
i.e. `:language`, `:region`, `:script`, `:variant`, etc.  
The resulting Locale object is the one
returned by a corresponding [[build]] call. See examples at [[build]].

* a **keyword** or **string**  
In this case the "specification" is splitted at "-" and "_" characters;  
the resulting Locale object is the one returned by
[[make-locale]] applied on the result of the splitting.

For more info see [[locale]].

General utility fns and macros used for creating Clojure wrappers of Java classes.