2. Merge with Xiao branch.

2. Add MemManager class to manage the memory;
3. Use the new version XList;
4. Add a new interface to create Tensor;
5. Apply MemManager to FNNLM.

1. fixed the bug in the Spread function.  2. add compare and OnehotAndIndex function 3. optimize the code

fix the bug of suming the word numbers of both source and target-sides for the loss computation in transformer MT models