Fix replies to messages with non-ASCII characters

Makefile

@@ -2,7 +2,7 @@
 
 COMMIT := $(shell git rev-parse --short HEAD)
 TD_COMMIT := "8517026415e75a8eec567774072cbbbbb52376c1"
-VERSION := "v1.7.5"
+VERSION := "v1.7.6"
 MAKEOPTS := "-j4"
 
 all:

telegabber.go

@@ -15,7 +15,7 @@ import (
 	goxmpp "gosrc.io/xmpp"
 )
 
-var version string = "1.7.5"
+var version string = "1.7.6"
 var commit string
 
 var sm *goxmpp.StreamManager

xmpp/handlers.go

@@ -149,7 +149,12 @@ func HandleMessage(s xmpp.Sender, p stanza.Packet) {
 							"end": body.End,
 						}).Warn(errors.Wrap(err, "Failed to parse fallback end!"))
 					}
-					text = text[:start] + text[end:]
+
+					fullRunes := []rune(text)
+					cutRunes := make([]rune, 0, len(text)-int(end-start))
+					cutRunes = append(cutRunes, fullRunes[:start]...)
+					cutRunes = append(cutRunes, fullRunes[end:]...)
+					text = string(cutRunes)
 				}
 			}
 			var replaceId int64