0.8.18.6401 - New Updated shaders! Fog Volume, PBS Color Mask, LUT filter

- Added PBS Color Mask shader (including both Metallic/Specular workflow) (requested by @Aegis_Wolf )
-- This material has a color mask texture, which allows selectively tinting 4 independent albedo/emissive regions
- Heavily extended Fog Box Volume shader (based on requests by @DeliriousJax and @Coffee )
-- It now supports 3 distance accumulation modes - Linear, Exponential and Exponential Squared
-- Linear mode now has Fog Start and Fog End properties
-- Added ability to use vertical color gradient instead of single accumulation Color
-- Added Worldspace mode, which computes accumulation in world distance units and doesn't clamp to the cube volume
-- Added Clamp Alpha and Clamp Color modes, which prevent color artifacts due to out-of-range alpha or HDR blow-out
- Added LUT filter shader (requested by @Coffee )
- Added support for exporting and importing LUT references
-- To export, simply grab an image, export as usual and select "LUT" as format (will be PNG file with LUTs embedded)
-- To import, simply use LUT option on the same image, which will import it as 3D texture, usable with the LUT filter shader
- Added "Disable Shadows" and "Disable Per Pixel Lights" to mirrors (suggested by @InsaneGrox )
- Added render time to debug dialog to help get more performance data diagnosis (based on feedback by @Addim)
-- This only works when running in VR
- Added Release All Grabbed node, which will force the player to release all held items in specific hand (implemented by @Coffee )


- Changed default camera far clipping distance to 4096 to correspond to VR clipping distance
-- This fixes the finger camera clipping part of the scene in large worlds (based on feedback by @Coffee)
- Headless Client doesn't run command server anymore (this prevents it from opening Neos links, reported by @Bom "Bitman" bomb (PolyLogiX) )
- Upgraded to Unity 2019.3b12


- Fixed race conditions when accessing world user data, causing certain things to randomly break (discovered in log from @Ballistic)
- Fixed excessive logging and exceptions in StatusManager triggered by a different error (discovered in log from @Ballistic)
- Removed forgotten debugging text when dragging out LogiX outputs with the tooltip (reported by @Hayden (PolyLogiX - ZyroDesign) )
- Removed some old logging information for P2P asset transfers
- Fixed textures with bpp larger than 24-bit (excluding alpha) not exporting correctly as JPG
- Fixed export dialog disappearing too soon
- Fixed texture data being flipped upside down in some cases
-- E.g. this fixes all procedural textures being flipped upside down
-- Also fixes certain cases where doing operations on textures (e.g. exporting or transforming) flips them upside down
- Fixed 3D Textures not respecting the clamp settings
- Fixed Patreon update not working correctly (based on issue by @Thorodiki )