first pass at a "builder" interface

build/global.go

@@ -0,0 +1,9 @@
+package build
+
+import "os"
+
+// ctx provides a global build context.
+var ctx = NewContext()
+
+func TEXT(name string) { ctx.TEXT(name) }
+func EOF()             { ctx.Generate(os.Stdout, os.Stderr) }