Ability to turn off logging

[wooster0]

Would be nice if I could turn off logging to the terminal. I always get two lines and a newline about it failing to "CreateInstance in ICD 1" and it having found the Vulkan backend. Everything works fine so I would like to just turn off logging but I'm not sure how to do so. As for any error it'd be nice if it returned an error union instead of printing something to the console so I can handle it. Currently it's using log.err followed by a std.process.exit(1) in a bunch of places and I'm not sure that's the best it can do. Maybe I don't want to have my process exited when Mach failed to initialize.