Move everything under the guecs/ directory in src/ so that it meshes better with other projects.

src/sfmlbackend/backend.cpp

@@ -1,38 +0,0 @@
-#include "sfmlbackend/backend.hpp"
-#include "sfmlbackend/shaders.hpp"
-#include "sfmlbackend/sound.hpp"
-#include "sfmlbackend/textures.hpp"
-
-namespace sfml {
-  guecs::SpriteTexture Backend::texture_get(const string& name) {
-    auto sp = textures::get(name);
-    return {sp.sprite, sp.texture};
-  }
-
-  Backend::Backend() {
-    sound::init();
-    shaders::init();
-    textures::init();
-  }
-
-  void Backend::sound_play(const string& name) {
-    sound::play(name);
-  }
-
-  void Backend::sound_stop(const string& name) {
-    sound::stop(name);
-  }
-
-  std::shared_ptr<sf::Shader> Backend::shader_get(const std::string& name) {
-    return shaders::get(name);
-  }
-
-  bool Backend::shader_updated() {
-    if(shaders::updated($shaders_version)) {
-      $shaders_version = shaders::version();
-      return true;
-    } else {
-      return false;
-    }
-  }
-}