Add instructions to build

[raphaklaus]

Hello! Is there any instruction to build this tool? I've checked that it is compatible with qtCreator, but I don't have this one.

Also, would be cool to add some instructions to the README.md about this.

[p4plus2]

What operating system? Though the tool is very early stages, but as a viewer fully funtional right now.

[raphaklaus]

Linux and Windows.