Remove useless function Graphics::textboxcleanup()

It was made useless after my refactor to remove the 'active' system from
text boxes.

desktop_version/src/Graphics.cpp

@@ -606,7 +606,6 @@ void Graphics::drawtowertile3( int x, int y, int t, int off )
 
 void Graphics::drawgui()
 {
-    textboxcleanup();
     //Draw all the textboxes to the screen
     for (size_t i = 0; i<textbox.size(); i++)
     {
@@ -2630,10 +2629,6 @@ void Graphics::setwarprect( int a, int b, int c, int d )
 	warprect.h = d;
 }
 
-	void Graphics::textboxcleanup()
-	{
-	}
-
 void Graphics::textboxcenter()
 {
 	textbox[m].centerx();

desktop_version/src/Graphics.h

@@ -55,8 +55,6 @@ public:
 
 	void createtextbox(std::string t, int xp, int yp, int r= 255, int g= 255, int b = 255);
 
-	void textboxcleanup();
-
 	void textboxcenter();
 
 	void textboxcenterx();