Add useful whisper features

[thewh1teagle]

Ordered by importance

• [ ] Start and stop timestamps for each segment
• [ ] New segment decoded callback (or I would like to know better how to stream decode efficiently as whisper has 30s limit)
• [ ] Progress callback? in case of long decode
• [ ] Abort callback? in case of long decode
• [ ] Word timestamps
• [ ] Translate
• [ ] Temperature
• [ ] Initial prompt