* add pad func

* add pad

* test=develop, add pad op and apis

* restore pad2d

* test=develop, fix paddl declare

* fix pad interface

* test=develop, fix pad

* test=develop, add all pad api and cos_sim

* test=develop, remove padding default value

* test=develop, rename var to tensor

* test=develop, add more tests

* test=develop, rename tovar to totensor

* test=develop, fix init

* test=develop, add more test

* test=develop, add more tests

* logsigmoid and LogSigmoid, test=develop

* add elu gelu relu, test=develop

* update to_variable to to_tensor, test=develop

* address review comments, test=develop

* address review comments, test=develop

* change to_variable to to_tensor in test, test=develop

add nn.functional.normalize API for API2.0, fix L1Loss API typo, test=develop

* add nll loss API, update demo code of the comment

* upate the target to label, test=develop

* Update the code for the margin_ranking_loss, test=develop

Update the sigmoid, Sigmoid layer for the api2.0

* expose and unify the Tensor concepts to the user

* expose tensor to user

* add copy place for Tensor

* add copy place for Tensor

* add note

* add macro PADDLE_WITH_CUDA

* remove RUN_TYPE=DIST

* fix some error

* add Class KLDivLoss and function kl_div

* add paddle.nn.functional.mse_loss

* add name

* fix conflict

add the api and doc for the margin_ranking_loss and MarginRankingLoss

* add nll loss API, update demo code of the comment

fix paddle.nn.loss.L1Loss OP, add paddle.nn.functional.l1_loss OP for API2.0

* test=develop update interpolate & upsample api

* add alias in paddle.nn and paddle.tensor test=develop

* add alias in paddle.nn and paddle.tensor dir test=develop

* fix same conflict manually test=develop

* update fc and dygraph alias test=develop

* fix initalizer.py typo test=develop

* add base name alias; test=develop

* fix embedding bug; test=develop

* fix io error; test=develop

* add metric; test=develop

* add import palce; test=develop

* add setup; test=develop

* fix incubate reader; test=develop

* fix initializer error; test=develop

* test=develop add linear interpolate operator

* define fluid alias in paddle.tensor and paddle.nn dir test=develop

* from layer import loss in paddle.nn dir test=develop

* add diag_embed op, test=develop

* add TestCase of diag_embed API

* Modified diag embed python API teastcase from dygraph to static graph, test=develop

* delete useless log and trigger ci, test=develop

* modified float16 of diag_embed, test=develop

* modified en doc of diag_embed

* trigger ci, test=develop

* add fp16 in dtype check of python API, test=develop

* modified __init__ and fix a big, test=develop

* modified a test bug of test_bicubic_interp_op and test_trilinear_interp_op, test=develop

* modified to use one kernel on cpu and cuda, test=develop

* add nn.interpolate, test=develop

* fix interpolate typo, test=develop

* formate code, test=develop

* fix unitest, test=develop

* add test layers, test=develop

* add test layers, test=develop

* extract common function, test=develop

* reduce the threads for cuda10, test=develop

* update unitest, test=develop

* polish unitest, test=develop

* add dygraph test, test=develop

* format description, test=develop

* add 5D input check, test=develop

* fix doc, test=develop

* add approximation for gelu, test=develop

* add functional conv

* add test and doc for function convs, test=develop

* update ConvTransposeOp's InferShape and error message, test=develop

* add hsigmoid, row_conv in paddle.nn(functional and layer), test=develop

* fix hyperlinks in docstring

* add Conv/ConvTranspose layers in paddle.nn.layer, test=develop

* add example code in docstring, test=develop

* update unittests to work with test_runner, test=develop

* add functional conv

* add test and doc for function convs, test=develop

* update ConvTransposeOp's InferShape and error message, test=develop

* define alias in paddle dir and paddle.nn dir test=develop

* define alias in paddle.nn.functional dir test=develop

* define alias in paddle.tensor.__init__.py test=develop