Boat placement

The user can place his/her boats. Everything is functional about this point.
Implemented PLACE request and minimal server

This commit contains the implementation of a bunch of functions so the game is
able to send its PLACE requests. Besides, a temporary server application has
been created. It does nothing particular, but is able to receive requests and
print them, for testing purposes.

Adresses are hardcoded to the loopback address (127.0.0.1) and port 5000.
Fix

Fixed a slight bug about the '\0' character at the end of sent requests which
was missing in particuliar situations.
Firing implemented

After having placed all his/her boats, the player can now chose a square to
fire upon. The client application will send a `FIRE` request if the given
coordinates are consistent. The application will then wait for the server to
answer with a `HIT`or a `MISS` request and then update its tracking grid
accordingly.

However, since the application only waits for one response, it will not catch
any `SINK` request by now. This improvement is to be done later.
Network layer improved

From now, the client application is able to recieve multiple answers from the
server for every synchronous request it sends.

The only remaining weak spot is asynchronous requests (which may only contain
`CHAT` requests), which are still ignored for the moment.
Merge branch 'feature-network-layer' into feature-game-kernel

Synchronous requests are now working and will be very useful in the development
of the game kernel.
Merge branch 'feature-game-kernel' into develop

Game kernel is working. Next step is to implement the overall network kernel.