switch json serializer when keepNull is false.
fixed typo.
add support: simpleFirstExample
rename method.
add support: simple-all, simple-by-example.
rename method.
add support: simple-any.
add support: simple-range API.
add support: remove-by-example API.
add support: simple-replace-by-example API.
add testcase for simple-replace-by-example
add support: simple-update-by-example API.
update todo.
update todo.
refactoring.
Add README in English.