Document the coding style about modmesh

[tigercosmos]

Let me provide some points:

• We are using snake case for functions and variables for non-QT-related code
• need to have /* end of xxx */ where xxx is a namespace or class.
• follow the rule of 5
• follow doxygen comment style
• comment for reference is highly recommend
• class member start with m_.
• macro start with DECL_MM_.

[ThreeMonth03]

@ThreeMonth03 I will try to put together a style guide by following your attempt in #362.

Thank you, I look forward to seeing the guideline.

[ThreeMonth03]

I think we could refer the Google C++ Style Guide,
and write the simpler guide for modmesh.

I will pull the draft by 6/10(Mon.).

In the draft, I expect it will list the guide about naming, comments and formatting.

[ThreeMonth03]

I think we could refer the Google C++ Style Guide, and write the simpler guide for modmesh.

I will pull the draft by 6/10(Mon.).

In the draft, I expect it will list the guide about naming, comments and formatting.

Here is a simple draft.
#362 (review)

[yungyuc]

@ThreeMonth03 I will try to put together a style guide by following your attempt in #362.

[yungyuc]

Fixed by #394

[yungyuc]

I created #395 for further discussions on the coding style.