Add new algorithm for Bilateral

Bilateral: Add new Bilateral algorithm with truncated spatial window and
sub-sampling, which is more suitable and faster for small sigmaS and
small sigmaR.
Bilateral: New parameter "int[] algorithm", when set to 0, it will
select appropriate algorithm according to sigmaS, sigmaR and PBFICnum.
Use aligned_malloc instead of new for image buff.
Default parameters were changed.
Destructor and some member functions were added to Data class, for
neater and safer code in VapourSynth interface.