1. Add mutex when operating the memory pool.
2. Support CMake 3.19 and fix some CMake bugs. Note that CUDA_ROOT variable in CMake is modified as CUDA_TOOLKIT_ROOT. You can find this update in the README.
3. Fix some bugs on Ubuntu.

1. Add mutex when operating the memory pool.
2. Support CMake 3.19 and fix some CMake bugs. Note that CUDA_ROOT variable in CMake is modified as CUDA_TOOLKIT_ROOT. You can find this update in the README.
3. Fix some bugs on Ubuntu.

Fix the minor bugs in Transformer.

1. Update the codes of machine translation sample. The current version is the same with NiuTrans.NMT.
2. Update the XList class.
3. Bugs fix.

Support fp16 data type for more operations and fix the minor errors.  (Don't use this! It's an incomplete version)

Update the Transformer codes.

1. Supporting efficient propagate and gradient accumulation for backward functions.
2. Update the setData functions.
3. Clean the codes.

Use tensor as the bottom implementation and support plain scalar.
Note: DO NOT support the backward for ReduceSumAll function.

1. Move the New/Initial/Del Tensor functions from XTensor.* to XElement.*
2. Move IsSameShaped functions from XTensor.* to core/shape/IsSameShaped.*
3. Move CheckData functions from XTensor.* to core/utilities/CheckData.*

2. fix the bug of onehotandindex
3. modify the data initilization of transformer
4. add the DumpFormat (need reimplement)

1. Merge with Huchi branch (replace all requireLink with enableGrad that allows gradient computation for a tensor);
2. Update the global memory size (This may make the memory size a little bit larger than the old version).

1. Global mem mode updated;
2. XTensor function updated to v2 interface;
3. Transformer model updated to v2 interface;
4. FNNLM bug fixed;
5. Other little bugs fixed.