Mapbase v5.1

- Fixed a major oversight in Source 2013 which was causing some code to think all logic entities were worldspawn
- Added WIP background nodraw for point_cameras set to not draw skybox at all
- Fixed map-specific talker not flushing on restore
- Added optional HUD hint to code-based game instructor hints
- Added workaround for suspicious crashes in HL2 NPC rappelling code (reported by 1upD)
- Made antlions summoned by npc_antlionguard report as dead when removed with the "Kill" input
- Fixed math_mod not saving mod value (reported by Klems)
- Added SDK_WindowImposter, which uses the SteamPipe cubemap bug workaround and includes support for parallax corrected cubemaps
- Updated thirdpartylegalnotices.txt to mention the Squirrel API
- Fixed incorrect type checking for script instances in VScript
- Added a bunch of new misc. VScript constants
- Added a few new base VScript functions
- Added a separate "Clientside Script Language" keyvalue to worldspawn for VScript, allowing client scripts to use a different language from server scripts
- Fixed worldspawn crashing the game when running entity scripts (reported by krassell)
- Fixed manifests creating a second worldspawn, allowing them to function properly in HL2
- Added tons of remapping-related fixes for instances and manifests, including node IDs and overlay remapping
- Added a keyvalue to func_instance which allows vector axis lines to be remapped properly
- Added support for manifest root path instances in VBSP
- Added missing PrintBrushContents() contents to VBSP
- Added -nohiddenmaps parameter
- Made manifest cordon somewhat functional

sp/src/game/server/ai_behavior_rappel.cpp

@@ -303,7 +303,14 @@ void CAI_RappelBehavior::GatherConditions()
 	if( HasCondition( COND_CAN_RANGE_ATTACK1 ) )
 	{
 		// Shoot at the enemy so long as I'm six feet or more above them.
+#ifdef MAPBASE
+		// There seems to be an underlying issue here. COND_CAN_RANGE_ATTACK1 should not be valid without an enemy,
+		// but crashes have been reported from GetEnemy() returning null in this code.
+		Assert( GetEnemy() );
+		if( GetEnemy() && (GetAbsOrigin().z - GetEnemy()->GetAbsOrigin().z >= 36.0f) && GetOuter()->GetShotRegulator()->ShouldShoot() )
+#else
 		if( (GetAbsOrigin().z - GetEnemy()->GetAbsOrigin().z >= 36.0f) && GetOuter()->GetShotRegulator()->ShouldShoot() )
+#endif
 		{
 			Activity activity = GetOuter()->TranslateActivity( ACT_GESTURE_RANGE_ATTACK1 );
 			Assert( activity != ACT_INVALID );