Handles length should be a per-project setting

Different projects may require different handle lengths. It doesn't really make much sense to me to put that in the User's preferences. It should be configurable at the Project level. It should also be possible to specify a different handle length on a per-clip basis.
For instance, if there is a time remap of some kind happening, the clip might require much longer handles to account for compression at the head or tail. This was a common situation for us on Teen Wolf, where they often, but not always, shot at 120 fps to allow time ramps and slow motion. Some shots then required 60 frames of handle instead of the more typical 12.
We have also had clients change their handles requirements mid-project, so it would be useful to be able to set new handles after the fact.
For instance, if there is a time remap of some kind happening, the clip might require much longer handles to account for compression at the head or tail. This was a common situation for us on Teen Wolf, where they often, but not always, shot at 120 fps to allow time ramps and slow motion. Some shots then required 60 frames of handle instead of the more typical 12.
We have also had clients change their handles requirements mid-project, so it would be useful to be able to set new handles after the fact.