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

1. add gather function 2. add cross entropy forward computation and backward computation 3. code optimization 4. merge with xiaotong-working branch

1. Bug fixed; 2. Support abs, sign, convert data type(float <->int) ;3. Merge with xu and xiao branch

1. Support check data with tolerance, get data from n dim with int format; 2. Bug fixed; 3. Format correction; 4. New tests