Remove the dirt from the Flak 38 sight overlay

[DHFan45]

Is your proposal related to a problem?

All vehicle sights/periscopes in DH are clean and clear. Only the sight used for all german Flak 38 guns is dirty. Under certain lighting conditions and depending on the weather and ground texture of the map, the dirtiness of the sight has a very negative effect on the player's view. In some situations this can have an unbalanced effect.

Describe the solution you'd like

Remove the dirt from the sight.

Additional context

[cmbasnett]

Unfortunately the original gun sight source file has long been lost, so removing the dirt might effectively mean just remaking the sight from scratch. This is obviously not hard, but someone has to find the time to do it.