Sub-to srt now sorts on timecodes

[jameshale]

I have just updated the sample stack "Sub-to-Srt"
The Re-Index button will now:
1. Delete empty text entries,
for those srt file where I did a global deletion of all SDH entries
and
2. order the file based on ascending start times.
I did this to allow me to combine an English srt with an English Forced srt.
Simple append one file to the other (in a text editor) and then read it in to Sub-to-Srt and click the Re-Index button.