1.4 Update
Fixed an issue that scroll doesn't smooth but clattered when on low fps.

1.3 Update
Fixed an issue that function AddScroll always return false even though the panel is scrolled. It causes inconvenience when scrolling panels that overlap each other.

1.2 Update
Fixed an issue that scrolling get stuck when in the game menu in a single player game.
Default scroll amount has changed from 25 to 30.

1.1 Update
Put code in just one lua file. so clean.
Remove 'print' that was used for test. TOO CLEAN.