Consider modifying LaserFrame to return views into allocated arrays

[clorton]

Currently users have to use the count property of a LaserFrame to determine how many slots are active. It might be good syntactic sugar for lf.property to actually return lf.property[0:lf.count] so the user doesn't have to do that each time.

Might require "property" to be allocated internally as "_property" to get access to the full array while lf.property returns the view.

I.e.,

lf.add_scalar_property("property") -> setattr(self, "_" + name, np.full(self._capacity, default, dtype=dtype))
lf.property -> lf._property[0:lf.count]