Invisible Target improvements

[commy2]

When merged this pull request will:

• Adds LandContact and Geometry LODs to InvisibleTarget.p3d, which should
• fix Using invisible targets on dedicated server results in server crash #1331
• Adds InvisibleTargetVehicle.p3d, which is the same as the other model, except with FireGeometry, so the object can be used as
• Vehicle Target & Air Target classes for all 3 sides, which
• closes Invisible vehicle targets #1340
• The InvisibleTargetVehicle.p3d P3D uses a cloth material, so the hit effect is minimal (almost unnoticable)

Please test if the crash is resolved.

[PabstMirror]

before dedi would hardlock for ~2 minutes, with client just showing "Wait for host" - see timecodes on server rpt

11:37:58 [CBA] (xeh) INFO: [4513,54.209,0] PreInit finished.
11:39:50 [CBA] (xeh) INFO: [4520,166.826,0] PostInit started. MISSIONINIT: missionName=testCBA-invis, missionVersion=53, worldName=Stratis, isMultiplayer=true, isServer=true, isDedicated=true, CBA_isHeadlessClient=false, hasInterface=false, didJIP=false

after: - almost no delay

11:41:09 [CBA] (xeh) INFO: [2796,31.631,0] PreInit finished.
11:41:09 [CBA] (xeh) INFO: [2803,32.227,0] PostInit started. MISSIONINIT: missionName=testCBA-invis, missionVersion=53, worldName=Stratis, isMultiplayer=true, isServer=true, isDedicated=true, CBA_isHeadlessClient=false, hasInterface=false, didJIP=false

[commy2]

So #1331 is not a crash, but a temporary freeze?