Implemented MSON section parsers

Please merge. This PR implements all related MSON section parsers.
This is unfortunate name and really easy to be confused with `MemberType` consider 

```c++
    /** Member type of a structure */
    struct MemberType {

```

and 

```c++
    /** Members type */
    struct Members {
```

This is not really saying anything. Please consider different name or at least a thoughtful explanation in the comments.