fill out the easy parts of the codegen

cmd/genql/main.go

@@ -1,16 +1,9 @@
 package main
 
 import (
-	"fmt"
-	"os"
-
 	"github.com/Khan/genql/generate"
 )
 
 func main() {
-	err := generate.Generate()
-	if err != nil {
-		fmt.Println(fmt.Errorf("genql failed: %v", err))
-		os.Exit(1)
-	}
+	generate.Main()
 }