New gui and bug fixes

New gui

The last commits were focused on gui improvement: now the game uses raygui (raylib gui) instead of my own gui implementations.

Bug fix

When the game was closed by the other player, the communications thread was still opened, now this is fixed and all the threads will be killed

Directory tree reorganized and new makefile

For who downloads the source code instead of the precompiled binary, the directory structure was reorganized so it is simpler to understand.
The makefile also got some improvements