Use tabs instead of spaces.
Qualify class names to satisfy compiler (MinGW/g++) requirements.

So that Divida::Person doesn't conflict with Beneficiary::Person (const std::shared_ptr<Person> Beneficiary::Person() const), etc.
Fix spacing.
Add missing include header.
Clean up precompiled header; use include guards instead of #pragma once to keep MinGW/g++ happy (issues a warning otherwise).
Use tabs instead of spaces in project file.
Update compilation flags to be platform specific.
Remove and ignore project user files (*.pro.user).