Merge pull request #108 from DanielHeath/mutex-save

Add mutex around page.Save(), fixes #70

page.go

@@ -8,6 +8,7 @@ import (
 	"regexp"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/schollz/versionedtext"
@@ -107,7 +108,11 @@ func (p *Page) Render() {
 	p.RenderedPage = MarkdownToHtml(p.Text.GetCurrent())
 }
 
+var saveMut = sync.Mutex{}
+
 func (p *Page) Save() error {
+	saveMut.Lock()
+	defer saveMut.Unlock()
 	bJSON, err := json.MarshalIndent(p, "", " ")
 	if err != nil {
 		return err