The equality of samples is generally used to compare the sample
equality, not its full properties. For instance, we don't compare
`Volume` in the base implementation.
Having `IsLayered` here breaks actual usages of equality, ie. for
pooling purposes.
The subscription in which the guards were present was moved from
constructor to `ApplyDefaults()`, and at that point neither the sample
control point or the difficulty point can be the default point, because
there are explicit paths that overwrite those with blank points in the
same methods, prior to the subscription's registration.
The only worry would be that someone would set the default point on the
object themselves, but at that point that is most likely programmer
error anyhow.
In editor contexts, the `StartTimeBindable` subscription in `HitObject`
was firing before defaults were applied, which in the case of sliders
manifested in an infinite end time. `ApplyDefaults()` also did not
always set the time of the control point to the correct value, which
matters when the beatmap is encoded.
Ensure that the control points receive the correct time values during
default application, and only register the `StartTimeBindable` change
callback after defaults have been successfully applied.
Previously the slider path length would be snapped using the current
beat snap setting on *every* change of the slider path. As it turns out
this is unexpected behaviour in some situations (e.g. when reversing a
path, which is expected to preserve the previous duration, even though
the slider may be technically "unsnapped" at that point in time due to a
different beat snap setting being selected afterwards).
This is quite a breaking change, but I think it is beneficial due to the large amount of usage of this class.
I originally intended just to remove the allocations of the two delegates handling the `Changed` flow internally, but as nothing was really using the bindables for anything more than a general "point has changed" case, this felt like a better direction.
With the previous commit, the transform application is skipped when the state is already changed. But it turns out the previous commit breaks slider animation in the standard editor. This is probably due to the transforms are applied before nested hit objects are added.
