ethutil: remove Config variable

Various functions throughout the codebase used it to grab settings. This
has to stop because I want to use them without reading the config file.

These functions can now be used without reading the config first:

* ethdb.NewLDBDatabase
* ethrepl.NewJSRepl
* vm.New

vm/vm.go

@@ -30,10 +30,7 @@ type Vm struct {
 
 func New(env Environment) *Vm {
 	lt := LogTyPretty
-	if ethutil.Config.Diff {
-		lt = LogTyDiff
-	}
-
+	// lt = LogTyDiff
 	return &Vm{debug: true, env: env, logTy: lt, Recoverable: true}
 }