Improve Introductory C++ Documentation

[Lagombi01]

The introductory documentation for the C++ version of Panda3D assumes an understanding of how to configure Visual Studio and can be unclear in other places. This makes it hard to learn how to compile and run even basic programs like the subsequent tutorial.
This could be fixed with some basic editions such as clearer paths for options in VS (such as "Project -> project name Settings" for finding configuration options) and more images for showing where certain fields can be found.