Fix some bugs

Issue : #22 NumPad not available;

- Fix compilation issue introduce with previous commit
- Fix issue of looping effect when play/pause with NumPad 4 key
- Fix software crash issue when user attemp to move time code if there
aren't subtitles
- Fix software crash issue when user delete a line
- Fix issue on border display when adding a new line
- Disable line auto wrap

Signed-off-by: juiice <decaen.julien@gmail.com>