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Adds a simple dynamic allocation scheme

This should help on highly tonal signals by increasing the rate of
bands with a lot more energy than the neighbouring bands.

--- a/libcelt/celt.c

+++ b/libcelt/celt.c

@@ -861,6 +861,36 @@

    for (i=0;i<st->mode->nbEBands;i++)

       offsets[i] = 0;

+   {

+      int t1, t2;

+      if (LM <= 1)

+      {

+         t1 = 3;

+         t2 = 5;

+      } else {

+         t1 = 2;

+         t2 = 4;

+      }

+      for (i=1;i<st->mode->nbEBands-1;i++)

+      {

+         if (2*bandLogE[i]-bandLogE[i-1]-bandLogE[i+1] > SHL16(t1,DB_SHIFT))

+            offsets[i] += 1;

+         if (2*bandLogE[i]-bandLogE[i-1]-bandLogE[i+1] > SHL16(t2,DB_SHIFT))

+            offsets[i] += 1;

+      }

+   }

+   for (i=0;i<st->mode->nbEBands;i++)

+   {

+      int j;

+      ec_enc_bit_prob(enc, offsets[i]!=0, 1024);

+      if (offsets[i]!=0)

+      {

+         for (j=0;j<offsets[i]-1;j++)

+            ec_enc_bit_prob(enc, 1, 32768);

+         ec_enc_bit_prob(enc, 0, 32768);

+      }

+      offsets[i] *= (6<<BITRES);

+   }

    bits = nbCompressedBytes*8 - ec_enc_tell(enc, 0) - 1;

    codedBands = compute_allocation(st->mode, st->start, st->end, offsets, bits, pulses, fine_quant, fine_priority, C, LM);

@@ -1534,6 +1564,16 @@

    for (i=0;i<st->mode->nbEBands;i++)

       offsets[i] = 0;

+   for (i=0;i<st->mode->nbEBands;i++)

+   {

+      if (ec_dec_bit_prob(dec, 1024))

+      {

+         while (ec_dec_bit_prob(dec, 32768))

+            offsets[i]++;

+         offsets[i]++;

+         offsets[i] *= (6<<BITRES);

+      }

+   }

    bits = len*8 - ec_dec_tell(dec, 0) - 1;

    ALLOC(fine_quant, st->mode->nbEBands, int);