Rename MatDim to MatDescriptor

timeline for distributed training

Add comment to explain how to run inference test

fix fluid Metric

* init

* init

* add ut

* split singleton from base class

* add singleton

* ad singleton

Correct tensor copy misuse

Add the call of DropKids at the end of executor.Run to delete the local scopes created in operators (#10403)

* Add the call of DeleteScope to delete the memory of scope created by NewScope.

* Call DropKids at the end of executor.Run to delete all local scopes created in operators.

Feature/update sparse parameter

* adding operator to blas deps list

* use device_context instead to solve cycle deps

* "optimizer op support float64"

* "fix ci"

* "fix ftrl op"

* Load/save the params from the params_path

* Switch to use load_persistables and save_persistables

* Instaed of setup the executor to run program and scope. Pass the program to the load_persistables

Fluid new API: dist train without modifying code

Wrap shfl_x_sync

* fix remove op

* update

Polish MatMul, clean copy & paste code

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into feature/update_sparse_parameter