world: Use context at contruction to simplify it's call

src/world.cpp

@@ -12,9 +12,13 @@
 
 // Constructor and destructor
 
-World::World(int width, int height) : _width(width), _height(height) {
+World::World(gol::ctx &context) {
+  _width = context.config_json["screen_width"].get<int>() /
+    context.config_json["cell_size"].get<int>(); 
+  _height = context.config_json["screen_height"].get<int>() /
+    context.config_json["cell_size"].get<int>();
   // create world data
-  this->_data = new std::vector<bool>(width * height, false);
+  this->_data = new std::vector<bool>(_width * _height, false);
 }
 
 World::~World() { delete this->_data; }