JANK MODE: Messy / broken commit - in progress

Needed to make a checkpoint, gods forgive me for committing known broken code straight to master. The jam has in a sense already begun.

I tested a smaller solution in the xplat_concept repo earlier today.
In short, I'm going to build a janky method to add new + report existing UI elements. After that's done, the UI building should be done from python modules, hastening the UI design.

This is ugly and bad, I am truly sorry. We just need to get through 7DRL, so I can't make it pretty today.

src/UIMenu.cpp

@@ -1,4 +1,5 @@
 #include "UIMenu.h"
+#include "Common.h"
 
 UIMenu::UIMenu(sf::Font & _font)
 : font(_font)
@@ -18,6 +19,7 @@ void UIMenu::render(sf::RenderWindow & window)
         window.draw(c);
     }
     for (auto& b : buttons) { b.render(window); }
+    for (auto& s: sprites) { window.draw(s); }
 }
 
 void UIMenu::refresh()
@@ -46,3 +48,9 @@ void UIMenu::add_button(Button b)
     next_button += 50;
     buttons.push_back(b);
 }
+
+void UIMenu::add_sprite(sf::Sprite s)
+{
+    sprites.push_back(s);
+}
+