Refactored the operator overloading example, fixed some grammar mistakes, reordered parts of the code
to make it easier to read and some other minor fixes.
* Removed whitespace in variable declaration with explicit type (Kotlin)
* Removed whitespace in variable declaration with explicit type (Kotlin translations)
* kotlin: remove unnecessary semicolons.
Also replace code block language `java` with `kotlin`.
* kotlin: change coding style (Kotlin Reference)
* kotlin: anonymous function -> lambda expression
Anonymous functions and lambda expressions are different in Kotlin.
The code example uses `anonymous function` in the comment,
while the code below is in fact lambda expressions.
* Remove myself from contributors.
Not for trivial changes.
* kotlin: fix a typo.
Thanks @geoffliu to point out this.
* kotlin: change style of default parameter according to Referenec.
* [kotlin/en] Add "if" usage as a function
* [kotlin/en] Change comment on "if" expression
Rephrase the comment to use the term "expression" in place of "function"
