Added check for maximum messages in the slice.

If more than 100 is present send the first 100 in the request and
ignore the rest.

restapi.go

@@ -1111,7 +1111,7 @@ func (s *Session) ChannelMessageDelete(channelID, messageID string) (err error)
 // If only one messageID is in the slice call channelMessageDelete funciton.
 // If the slice is empty do nothing.
 // channelID : The ID of the channel for the messages to delete.
-// messages  : The IDs of the messages to be deleted. A slice of string IDs.
+// messages  : The IDs of the messages to be deleted. A slice of string IDs. A maximum of 100 messages.
 func (s *Session) ChannelMessagesBulkDelete(channelID string, messages []string) (err error) {
 
 	if len(messages) == 0 {
@@ -1123,6 +1123,10 @@ func (s *Session) ChannelMessagesBulkDelete(channelID string, messages []string)
 		return
 	}
 
+	if len(messages) > 100 {
+		messages = messages[:100]
+	}
+
 	data := struct {
 		Messages []string `json:"messages"`
 	}{messages}