Add clouds and rain

[salmo]

Here's an annotated example from the weather section of a mission file.

[LocalWeather_0]
EllipticA 20000 // size of weather zone in X-axis
EllipticB 5000 // size of weather zone in Y-axis
RotAngle 0 // rotation vector for weather zone elipse
ShiftX 0 // unknown (?could be an elipse tilt vector)
ShiftY 0 // unknown (?could be an elipse tilt vector)
BaseHeight 700 // height (metres) of weather elipse
IsRain 0 // 1=rain (but not working yet)
IsDynamicEnabled 1 // Unknown
ParticipType 1 // Unknown (?not working)
DropSize 0 // Unknown (?not working)
RainPower 0 // unknown (?not working)
ThermalIntensity 10 // ?alter degree of temperature gradient/'icing'- 10 =full icing
CloudsDensity 5 // set dense of coud formations
MidSize 5 // ?alter size of 'blocks' making cloud formation, more apparent as CloudDensity is reduced
EvenLayers 5 // a parameter to define how evenly weather layers are spaced
TotalLayers 15 // number of definable layers in the weather elipse
IsThunder True // set audible thunder (but not working)
FrontThickness 3500 // front thickness
FrontWindMaxHorSpeedNear 15 // maximum wind speed
FrontWindMaxVertSpeedUp 30 // maximum updraft wind speed
FrontWindMaxVertSpeedDown 20 // maximum downdraft wind speed
FrontWindMaxTurbInClouds 15 // maximum wind turbulance
FrontWindMaxTurbInSquallZone 20 // maximum wind turbulance in squals (?not working)