Still working on the widgets attribute

Can now corectly set multiple sprite to a widget
We can also chose to display a sprite in it's list or not by setting it's draw attr
Can now resize a widget, this will not move it (scale does), can also resize widget's sprite
Rearranged panels -> Created different types

Panels can now store other panels, that make them dependants (master / slave)
Made a Tabwidget, it is attached to a panel
Enhanced event system and conception
Moved Cvar to common dir

Need to addCvar somewhere else than the constructor
add a simple netcat server
Add a Network Class in the client
The server has now Cvar and can handle when it change
Add protobuf lib and resolve an error on ENet cmake module
Merge branch 'network' of github.com:izissise/PFA into network

Conflicts:
	client/src/Network.cpp
	server/inc/server.hpp
	server/src/Server.cpp
	server/src/client.cpp