Added Half-Life: Source difficulty configuration files

Added filter_activator_context and filter_activator_model entities

Changing skill level with Lua or the convar also runs/loads the appropriate skill config files

Added full support for Static Prop Lightmaps

Added $phong, $envmapLightScale and $envmapLightScaleMinMax parameter support for LightmappedGeneric shader

Added $phongAlbedoBoost parameter to VertexLitGeneric shader

Added $phongDisableHalfLambert parameter to VertexLitGeneric shader

Added $pp_colour_inv to g_colourmodify shader

Added $envmapsphere parameter to VertexLitGeneric, which restores how Half-Life: Source chrome materials render

Added input/output descriptions to "Entity Properties" window in Hammer

Added prop_sphere to Hammer and added radius keyvalue to it

Added func_friction to Hammer

Added 6 new inputs to all entities - SetLocalOrigin, SetLocalAngles, DisableDraw, EnableDraw, DisableReceivingFlashlight, EnableReceivingFlashlight

Added "Disable flashlight" keyvalue to all entities in Hammer

Added new inputs to func_tracktrain - SetMaxSpeed, MoveToPathNode, TeleportToPathNode, LockOrientation, UnlockOrientation

Added new output to func_tracktrain - OnArrivedAtDestinationNode

Added the following particle initializers - Position Along Ring, Position Along Epitrochoid, Position Modify Place On Ground, Position From Chaotic Attractor, Scalar Random, Vector Random, Vector Component Random, Set Hitbox to Closest Hitbox, Set Hitbox Position on Model, Velocity Set from Control Point, Remap Particle Count to Scalar

Added the following particle operators - Remap Direction to CP to Vector

Added the following global particle attributes - screen space effect, normal, Visibility input dot min/max, Visibility input distance min/max

Added "render models" particle renderer

Added "hitbox" and "hitbox set" parameters to - Movement Lock to Bone (operator), Cull relative to model (operator), as well as Position on Model Random (initializer) whose "hitbox scale" is now "model hitbox scale"