Also a bunch of comments

Now everything is done through quant_all_bands() and quant_band().

We prevent as many as possible, but they can still occur if we
manage to reach the LN limit

Uses a triangular PDF for coding the angle.

Folding now moved to alg_quant() and alg_unquant(). No more funny short block
alignment checks because bands now have to be aligned.

The main encode call no longer takes a pointer for the optional resynthesis.
It's now done with a call to celt_encode_resynthesis().

our search can now work on vectors that don't have unit norm