feat(input): Tie the state of the caps lock to the state of fast-forw…

…ard if caps lock is used as the fast-forward key (endless-sky#9676)

data/_ui/tooltips.txt

@@ -1183,7 +1183,7 @@ tip "Toggle fullscreen"
 	`Toggle whether the game is in fullscreen mode.`
 
 tip "Toggle fast-forward"
-	`Toggle a 3x speed fast-forward. Fast-forward may be automatically deactivated by the "Interrupt fast-forward" setting.`
+	`Toggle a 3x speed fast-forward. Fast-forward may be automatically deactivated by the "Interrupt fast-forward" setting. If the key is set to caps-lock then the caps-lock state will be used to determine the fast-forward state.`
 
 tip "Show help"
 	`Display the help dialogs that are relevant to your current UI panel and situation. Uses the same help dialogs from the "Reactivate first-time help" setting, forcing them to appear even if they have already appeared before.`

source/main.cpp

@@ -315,11 +315,17 @@ void GameLoop(PlayerInfo &player, const Conversation &conversation, const string
 				// The UI handled the event.
 			}
 			else if(event.type == SDL_KEYDOWN && !event.key.repeat
-					&& (Command(event.key.keysym.sym).Has(Command::FASTFORWARD)))
+					&& (Command(event.key.keysym.sym).Has(Command::FASTFORWARD))
+					&& !Command(SDLK_CAPSLOCK).Has(Command::FASTFORWARD))
 			{
 				isFastForward = !isFastForward;
 			}
 		}
+
+		// Special case: If fastforward is on capslock, update on mod state and not
+		// on keypress.
+		if(Command(SDLK_CAPSLOCK).Has(Command::FASTFORWARD))
+			isFastForward = SDL_GetModState() & KMOD_CAPS;
 	};
 
 	// Game loop when running the game normally.