Portal 2 - Update

An update has been released for Portal 2.

Improvements:   - Improved Vulkan implementation     - Overall performance improvements     - Massively improved performance with Anti-Aliasing (MSAA) on AMD   - Made the intro video skippable by any button on a Steam Controller   - Added controller glpyhs to the main menu when using a controller Bug Fixes:   - Fixed the Super 8 teaser not playing on Linux   - Fixed certain Unicode characters being displayed as garbage on Linux   - Fixed text corruption in the challenge mode UI on Linux   - Fixed a crash that could occur wrt. networking on Linux   - Fixed the text color in advanced video settings not respecting the dark panel UI variant   - Fixed Model/Texture detail defaulting to Low in Vulkan mode   - Fixed the challenge mode timer being cut off   - Fixed a crash after trying to play a demo without having the respective map   - Fixed a crash when trying to load invalid VPKs