- sequence strips without scenes would crash on display

- sequence strips without scenes would crash on display
- appending scenes would not append the sound and scene ID's for sequence strips
- reload button in sequence header now reloads sounds as well.
- redrawing the sequence image view didnt work while plaing (unless play was activated from that region)
- generic functions for running a callback on sequence strips recursively. seqbase_recursive_apply() and seq_recursive_apply()
- bind marker with camera was set to home key, use Ctrl+B instead.