Send Big File

Hi! 
Thanks for you library!
I try send file big file to server. I split file on chunks and send with this method:
```
TL_upload_saveBigFilePart{
	file_id:          id,
	file_part:        int32(i),
	file_total_parts: parts,
	bytes:            bb,
},
```
But after last chunk, I receive error from `readRoutine`:
```
ReadRoutine: EOF
```
Who knows what is problem?
