speed optimization #6
Description
Most of case, compression is the same befor changed.
`//// Encoder.java ////
line 165 - 167 is changed to below.
for (int i=symbolIndex;i>0;)nodes[--i].frequency+=symbolCount[i];
//// CanonicalHuffmanTree.java ////
line 40 is changed to below
depths[lastOccurrence = i]=0;
line 50 is changed to below
newFreqs[index][depths[index]++] = frequency;
line 52 - 75 is removed`