C++ Style Guide

[Kalashnikovni]

We've discussed some formatting details with @francosansone, so I thought it would be good to adopt a C++ Style Guide. I think that Google C++ Style Guide is a good reference.
I remember that @joaquinffernandez added hook files to enforce a specific layout, do they follow some other guide?

[joaquinffernandez]

The hook (once enabled) will apply the style defined here on the commit modified files. I have no particular preference, maybe once we agree on the details we can just bulk update the repo and apply the style to all the files, then after that we'll see only the modified code on each PR.

[francosansone]

I agree with this convention. I'd like to suggest only one modification:

According to the guide, private data members should have an underscore at the end, I would rather move it to the beginning.

class TableInfo {
 public:
  ...
  static const int kTableVersion = 3;  // OK - constant naming.
  ...

 private:
  std::string _table_name;             // OK - underscore at beginning.
  static Pool<TableInfo>* _pool;       // OK.
};

[Kalashnikovni]

I was against it at first, because it doesn't follow the current style adopted also in ModelicaCC. However, you're right pointing out that in this way private data member variables are easily identified at first glance.