feat: Add quit button to the menu (#99)

Adds a quit button to the main menu.

This option may feel nicer to some users over requiring the use of the
close button on the window.

I was hoping for a somewhat 'cleaner' way of doing this (such as by
manually triggering an `SDL_QUIT` event from the menu), but I have not
yet figured out if that is possible. If you have a better way of
handling this, feel free to close this PR or let me know. Otherwise, I
believe this should work fine.

Lamp/Menu/lampMenu.cpp

@@ -313,6 +313,9 @@ void Lamp::Core::lampMenu::DefaultMenuBar() {
                 ImGui::EndMenu();
             }
 
+            if (ImGui::MenuItem("Quit")) {
+                this->userRequestedQuit = true;
+            }
 
 
             ImGui::EndMenu();

Lamp/Menu/lampMenu.h

@@ -20,6 +20,7 @@ namespace Lamp::Core{
         };
 
         Menus currentMenu = LICENCE_MENU;
+        bool userRequestedQuit = false;
 
         void RunMenus();
 

main.cpp

@@ -177,6 +177,10 @@ int main(int, char**)
         SDL_RenderClear(renderer);
         ImGui_ImplSDLRenderer2_RenderDrawData(ImGui::GetDrawData());
         SDL_RenderPresent(renderer);
+
+        if(Menus.userRequestedQuit){
+            done = true;
+        }
     }
 
     ImGui_ImplSDLRenderer2_Shutdown();