GUI Changes
- Add alpha checkbox in the VTF preview controls to hide/show the alpha channel of a texture (thanks @Trico-Everfire!)
- Add tile checkbox in the VTF preview controls to display the texture tiled
- Add label to zoom slider in the VTF preview controls
General Changes
- Improve file handling to only request read or write access to a file when necessary. This should improve trying to read from a VPK when another process, like Hammer or a Source engine game, is using the VPK at the same time