Update 0.153a. New weather and time of day options.

New weather and time of day options have been added.
- A "Fog" slider has been added to Custom Battle screen.
- Thunderstorm and cloudy weather have been added to the Weather selector of the Custom Battle screen.
- The Morning and Evening Time of Day options of the Custom Battle screen have been divided into early and late morning/evening.
An artillery fire gong has been added for main guns of all ships except armed merchants. "Artillery fire gong" checkbox has been added to the Audio tab of the Settings screen to disable this effect.
The amount and duration of smoke of detonation particle effect has been slightly increased.
Slightly reduced structural damage from surface explosions.
A couple of minor UI changes have been made.
A couple of bugs have been fixed.