morph switch

[blancoberg]

Implemented switch for handling legacy vs new interpolation

I decided to move the actual calculations of the interpolations outside of convolute, to make it more clear if we for some reason decide to add more interpolation modes.

I then have a function pointer that is set on each block that points to the active interpolation function. I though that would be more optimal than having several if-statements inside of convolute().

I have also included the morph interpolation that I talked about yesterday. It is only used in cases where the morph value has changed more than 5 frames in a block. It works pretty well to reduce noise in those cases.
A nice side effect is that it also reduces the noise when changing value with GUI, as those stepped changes will now morph instead of scrub.

Addresses #7784 #7777 #7696

[baconpaul]

Oh that function pointer solution is very clever. Nice.

Let me merge this and then we can start asking nightly testers to look out for goobits.