refactor: hide piring package

This package is very low-level and because of that it is not very reusable. Hide it. At least for now, until someone will ask for it. Less public API means less chance to introduce a breaking change.

Author: elgopher

piring/piring.go renamed to internal/piring/piring.go

@@ -6,7 +6,7 @@ package piring_test
 import (
 	"testing"
 
-	"github.com/elgopher/pi/piring"
+	"github.com/elgopher/pi/internal/piring"
 )
 
 func BenchmarkBuffer_NextWritePointer(b *testing.B) {

piring/piring_bench_test.go renamed to internal/piring/piring_bench_test.go

@@ -6,9 +6,8 @@ package piring_test
 import (
 	"testing"
 
+	"github.com/elgopher/pi/internal/piring"
 	"github.com/stretchr/testify/assert"
-
-	"github.com/elgopher/pi/piring"
 )
 
 func TestBuffer(t *testing.T) {

piring/piring_test.go renamed to internal/piring/piring_test.go

@@ -5,7 +5,7 @@ package internal
 
 import (
 	"github.com/elgopher/pi"
-	"github.com/elgopher/pi/piring"
+	"github.com/elgopher/pi/internal/piring"
 )
 
 var theScreenRecorder = newScreenRecorder(128)