v1.4.1

1. perf: optimize Set::min/max
2. refactor: use utility::print() to reduce code
3. test: arrange tests with pyincpp: more and regular

This is a stable version and may not be updated for a long time.

v1.4.0

1. update readme
2. add test_demo
3. fix Set::partial_cmp: neither a subset nor a superset return None
4. add comments for pub struct
5. adjust Deque::len: usize -> i32 for negative index compatibility
6. add check for Deque::push
7. add Index/IndexMut for Deque
8. refine code
9. add Dict::find
10. adjust Dict::remove: Option -> bool
11. remove partial_cmp for Dict
12. let Int::new() has an empty Vec and optimize Int
13. adjust List::count: i32 -> usize
14. add Set::find
15. add Set::min/max
16. rename Set::insert -> Set::add
17. add Set::pop

manually "cherry-pick"ed with pyincpp

v1.3.0

1. Decoupling modules and eliminating redundant code.
2. Improve performance.
3. Add to_integer() for Str.
4. Add to_integer<T>() for Int.
5. Refine doc-comments.

v1.2.0

• add with_capacity() and reserve() for Deque.
• modify insert() and remove() return to indicate state for Set.
• optimize performance.

v1.1.0

1. add char_at(), +(), *() for Str.
2. refine readme.

v1.0.0

version 1.0.0 released!

v0.7.0

add type Int.

v0.6.0

add type Dict.

v0.5.0

1. add type Set.
2. completed conversion functions.
3. optimize the code structure.

v0.4.0

1. add type Deque.
2. rename size() -> len().
3. refine code.