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

Added support for dim equals 2 in activation functions

Rewrite memroy/detail

Fix debuger bugs

run prefetch prog on server

Fix seq tag model dist transpile

1. Combine 'open_files', 'multi_pass_reader' and 'threaded_reader'
together to make the new 'open_files' interface.
2. Add some docstring.
3. Simplify interface names of 'create_XXX_reader', e.g, rename
'create_double_buffer_reader' to 'double_buffer'.

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

Update reader

Move filemanager to `edl` repo.

Update release doc

1. Removes MultipleReader's multi-thread support, for we have got
ThreadedReader.
2. Rename MultipleReader to MultiFileReader

fix compiler error on `tensor_py.h`

fix missing core.so on mac