Use dep to vendor things

vendor/github.com/faiface/glhf/doc.go

@@ -0,0 +1,7 @@
+// Package glhf provides abstractions around the basic OpenGL primitives and operations.
+//
+// All calls should be done from the main thread using "github.com/faiface/mainthread" package.
+//
+// This package deliberately does not handle nor report trivial OpenGL errors, it's up to you to
+// cause none. It does of course report errors like shader compilation error and such.
+package glhf