PLT-6271 Changed word splitting to initially split on any non-name character (#6261)

* PLT-6271 Changed word splitting to initially split on any non-name character

* Fixed detection of out of channel mentions

app/user_test.go

@@ -5,9 +5,9 @@ package app
 
 import (
 	"bytes"
+	"encoding/json"
 	"image"
 	"image/color"
-	"encoding/json"
 	"math/rand"
 	"strings"
 	"testing"