Add an accessibility option to be able to see through the roomname

This is the variable dwgfx.translucentroomname and <translucentroomname>
in unlock.vvv.

This lets you see through the black background of the roomname at the
bottom of the screen, i.e. it makes the roomname background translucent.
So you can see if someone decides to hide pesky spikes there.

desktop_version/src/Graphics.cpp

@@ -122,6 +122,8 @@ Graphics::Graphics()
     trinketg = 0;
     trinketb = 0;
     warprect = SDL_Rect();
+
+    translucentroomname = false;
 }
 
 Graphics::~Graphics()